View Compilation Error

0_0_20446064_29583.cpp: In function 'int main()':
0_0_20446064_29583.cpp:12:5: error: 'set' was not declared in this scope
     set<int> gold;
     ^
0_0_20446064_29583.cpp:12:9: error: expected primary-expression before 'int'
     set<int> gold;
         ^
0_0_20446064_29583.cpp:16:9: error: 'gold' was not declared in this scope
         gold.clear();
         ^