View Compilation Error

0_0_15406217_18534.cpp:27:1: error: 'hash_map' does not name a type
 hash_map<LL,int>G;
 ^
0_0_15406217_18534.cpp: In function 'int main()':
0_0_15406217_18534.cpp:51:16: error: 'G' was not declared in this scope
                G.clear();
                ^