View Compilation Error

0_0_35330181_29951.cpp:9:1: error: 'unordered_map' does not name a type
 unordered_map<ll, bool> ump;
 ^
0_0_35330181_29951.cpp: In function 'int solve()':
0_0_35330181_29951.cpp:26:9: error: 'ump' was not declared in this scope
      if(ump[sum[i] + k] || ump[sum[i] - k]) _ = true;
         ^
0_0_35330181_29951.cpp:27:6: error: 'ump' was not declared in this scope
      ump[sum[i]] = true;
      ^
0_0_35330181_29951.cpp: In function 'int main()':
0_0_35330181_29951.cpp:51:3: error: 'ump' was not declared in this scope
   ump.clear();
   ^