View Compilation Error

0_0_37918697_7475.cpp: In function 'int main()':
0_0_37918697_7475.cpp:11:8: error: 'unordered_map' was not declared in this scope
        unordered_map <int,int> cnt;
        ^
0_0_37918697_7475.cpp:11:23: error: expected primary-expression before 'int'
        unordered_map <int,int> cnt;
                       ^
0_0_37918697_7475.cpp:15:13: error: 'cnt' was not declared in this scope
             cnt[tmp]++;
             ^
0_0_37918697_7475.cpp:19:17: error: 'cnt' was not declared in this scope
             if (cnt[tmp]!=0) ans++;
                 ^