View Compilation Error

0_0_17958294_1403.cpp:10:1: error: 'hash_map' does not name a type
 hash_map<int,int> mpt;
 ^
0_0_17958294_1403.cpp: In function 'int main()':
0_0_17958294_1403.cpp:28:3: error: 'mpt' was not declared in this scope
   mpt.clear();
   ^