diff --git a/include/element.h b/include/element.h
index a495472..c9eadf5 100644
--- a/include/element.h
+++ b/include/element.h
@@ -4,7 +4,6 @@
 #include <map>
 #include <memory>
 #include <set>
-#include <string>
 #include <utility>
 #include <vector>
 
@@ -12,7 +11,6 @@ using std::map;
 using std::pair;
 using std::set;
 using std::shared_ptr;
-using std::string;
 using std::vector;
 using std::weak_ptr;
 
@@ -26,8 +24,8 @@ struct Struct {
 	weak_ptr<Struct> fa;
 	vector<shared_ptr<TemplateType>> c1;
 	vector<shared_ptr<ValType>> c2;
-	map<string, shared_ptr<ValType>> vars;
-	map<string, shared_ptr<Struct>> structs;
+	map<int, shared_ptr<ValType>> vars;
+	map<int, shared_ptr<Struct>> structs;
 };
 
 struct ValType {
diff --git a/include/token.h b/include/token.h
index 427d56a..3308f95 100644
--- a/include/token.h
+++ b/include/token.h
@@ -30,11 +30,12 @@ enum class TokenType {
 };
 
 extern std::string token_mp[];
+extern std::vector<std::string> id_mp;
 
 struct Token {
 	int line;
 	TokenType type;
-	std::string s;
+	int s;
 };
 
 #endif
\ No newline at end of file
diff --git a/src/scan.cpp b/src/scan.cpp
index 31085ac..d5a54eb 100644
--- a/src/scan.cpp
+++ b/src/scan.cpp
@@ -1,4 +1,5 @@
 #include "scan.h"
+#include <map>
 
 using namespace std;
 
@@ -14,9 +15,11 @@ vector<Token> scan(string s) {
 			pt++;
 		}
 	};
+	map<string, int> mp;
 	for (skipSpace(); pt < s.size(); skipSpace()) {
 		TokenType type;
 		string t;
+		int id = 0;
 		if (s[pt] == ',') {
 			type = TokenType::COMMA, pt++;
 		} else if (s[pt] == ';') {
@@ -56,27 +59,32 @@ vector<Token> scan(string s) {
 			}
 			t = s.substr(pt, r - pt);
 			if (t == "struct") {
-				type = TokenType::STRUCT, t.clear();
+				type = TokenType::STRUCT;
 			} else if (t == "Fn") {
-				type = TokenType::FN, t.clear();
+				type = TokenType::FN;
 			} else if (t == "return") {
-				type = TokenType::RETURN, t.clear();
+				type = TokenType::RETURN;
 			} else if (t == "typeof") {
-				type = TokenType::TYPEOF, t.clear();
+				type = TokenType::TYPEOF;
 			} else if (t == "private") {
-				type = TokenType::PRIVATE, t.clear();
+				type = TokenType::PRIVATE;
 			} else if (t == "admit") {
-				type = TokenType::ADMIT, t.clear();
+				type = TokenType::ADMIT;
 			} else if (t == "delete") {
-				type = TokenType::DELETE, t.clear();
+				type = TokenType::DELETE;
 			} else {
 				type = TokenType::ID;
+				if(mp.find(t) == mp.end()) {
+					mp[t] = id_mp.size();
+					id_mp.push_back(t);
+				}
+				id = mp[t];
 			}
 			pt = r;
 		} else {
 			printf("error on line %d", line), exit(1);
 		}
-		tokens.push_back({line, type, t});
+		tokens.push_back({line, type, id});
 	}
 	return tokens;
 }
\ No newline at end of file
diff --git a/src/token.cpp b/src/token.cpp
index 98ad3cc..bf27f0b 100644
--- a/src/token.cpp
+++ b/src/token.cpp
@@ -1,7 +1,9 @@
-
 #include <string>
+#include <vector>
 
-std::string token_mp[] = {",",
+using namespace std;
+
+string token_mp[] = {",",
 			  ";",
 			  "{",
 			  "}",
@@ -22,3 +24,5 @@ std::string token_mp[] = {",",
 			  "admit",
 			  "delete",
 			  "ID"};
+
+vector<string> id_mp{""};
\ No newline at end of file
diff --git a/src/work.cpp b/src/work.cpp
index 542beb4..aa4e675 100644
--- a/src/work.cpp
+++ b/src/work.cpp
@@ -47,7 +47,7 @@ struct DefVar : Def {
 	shared_ptr<ValType> def_var;
 };
 
-map<string, shared_ptr<Def>> ndefs;
+map<int, shared_ptr<Def>> ndefs;
 
 bool preview(vector<TokenType> v) {
 	if (pt + v.size() > tokens.size()) {
@@ -63,7 +63,7 @@ bool preview(vector<TokenType> v) {
 bool preview(TokenType t) {
 	return preview(vector<TokenType>{t});
 }
-string jump(TokenType t) {
+int jump(TokenType t) {
 	if (preview(t)) {
 		return tokens[pt++].s;
 	}
@@ -81,10 +81,10 @@ vector<shared_ptr<ValType>> createVals();
 shared_ptr<ValType> _createType(shared_ptr<Struct>);
 shared_ptr<ValType> createType();
 vector<shared_ptr<ValType>> createTypes();
-vector<pair<string, shared_ptr<TemplateType>>> createTems();
-vector<pair<string, shared_ptr<ValType>>> createPars(map<string, shared_ptr<ValType>>* = nullptr);
-pair<string, shared_ptr<Struct>> createStruct();
-pair<string, shared_ptr<ValType>> createVar();
+vector<pair<int, shared_ptr<TemplateType>>> createTems();
+vector<pair<int, shared_ptr<ValType>>> createPars(map<int, shared_ptr<ValType>>* = nullptr);
+pair<int, shared_ptr<Struct>> createStruct();
+pair<int, shared_ptr<ValType>> createVar();
 
 shared_ptr<ValType> _createVal(shared_ptr<StructType> ft) {
 	auto str = ft->str;
@@ -137,7 +137,7 @@ shared_ptr<ValType> createVal() {
 	if (preview(TokenType::FN)) {
 		pt++;
 		auto tt = make_shared<FunctionType>();
-		vector<pair<string, shared_ptr<TemplateType>>> tems;
+		vector<pair<int, shared_ptr<TemplateType>>> tems;
 		if (preview(TokenType::LT)) {
 			tems = createTems();
 		}
@@ -152,7 +152,7 @@ shared_ptr<ValType> createVal() {
 		tt->c3 = createType();
 
 		jump(TokenType::LB);
-		vector<string> defs;
+		vector<int> defs;
 		while (!preview(TokenType::RETURN)) {
 			if (preview({TokenType::STRUCT, TokenType::ID})) {
 				defs.push_back(createStruct().first);
@@ -370,8 +370,8 @@ vector<shared_ptr<ValType>> createTypes() {
 	return types;
 }
 
-vector<pair<string, shared_ptr<TemplateType>>> createTems() {
-	vector<pair<string, shared_ptr<TemplateType>>> tems;
+vector<pair<int, shared_ptr<TemplateType>>> createTems() {
+	vector<pair<int, shared_ptr<TemplateType>>> tems;
 	jump(TokenType::LT);
 	if (preview(TokenType::ID)) {
 		auto single = [&]() {
@@ -391,8 +391,8 @@ vector<pair<string, shared_ptr<TemplateType>>> createTems() {
 	return tems;
 }
 
-vector<pair<string, shared_ptr<ValType>>> createPars(map<string, shared_ptr<ValType>>* vars) {
-	vector<pair<string, shared_ptr<ValType>>> pars;
+vector<pair<int, shared_ptr<ValType>>> createPars(map<int, shared_ptr<ValType>>* vars) {
+	vector<pair<int, shared_ptr<ValType>>> pars;
 	jump(TokenType::LP);
 	if (!preview(TokenType::RP)) {
 		auto single = [&]() {
@@ -418,11 +418,11 @@ vector<pair<string, shared_ptr<ValType>>> createPars(map<string, shared_ptr<ValT
 	return pars;
 }
 
-pair<string, shared_ptr<Struct>> createStruct() {
+pair<int, shared_ptr<Struct>> createStruct() {
 	jump(TokenType::STRUCT);
-	string s;
-	vector<pair<string, shared_ptr<TemplateType>>> tems;
-	vector<pair<string, shared_ptr<ValType>>> pars;
+	int s = 0;
+	vector<pair<int, shared_ptr<TemplateType>>> tems;
+	vector<pair<int, shared_ptr<ValType>>> pars;
 	auto t = make_shared<Struct>();
 
 	bool constructor = 1;
@@ -451,7 +451,7 @@ pair<string, shared_ptr<Struct>> createStruct() {
 	}
 
 	jump(TokenType::LB);
-	vector<string> defs;
+	vector<int> defs;
 	vector<shared_ptr<Struct>> subs;
 	while (!preview(TokenType::RB)) {
 		bool pub = 1;
@@ -489,7 +489,7 @@ pair<string, shared_ptr<Struct>> createStruct() {
 		ndefs.erase(ss);
 	}
 
-	if (!s.empty()) {
+	if (s) {
 		auto tt = make_shared<DefStruct>();
 		tt->def_struct = t;
 		ndefs[s] = static_pointer_cast<Def>(tt);
@@ -497,8 +497,8 @@ pair<string, shared_ptr<Struct>> createStruct() {
 	return {s, t};
 }
 
-pair<string, shared_ptr<ValType>> createVar() {
-	string s;
+pair<int, shared_ptr<ValType>> createVar() {
+	int s;
 	shared_ptr<ValType> t;
 	if (preview(TokenType::STRUCT)) {
 		auto pr = createStruct();