View Compilation Error

0_0_30112968_20540.cpp: In function 'int main()':
0_0_30112968_20540.cpp:95:13: error: 'hash_map' was not declared in this scope
             hash_map<pair<double, double>, int>g;
             ^
0_0_30112968_20540.cpp:95:13: note: suggested alternative:
In file included from 0_0_30112968_20540.cpp:2:0:
GCC4.9.2/x86_64-w64-mingw32/include/c++/backward/hash_map:83:11: note:   '__gnu_cxx::hash_map'
     class hash_map
           ^
0_0_30112968_20540.cpp:95:42: error: expected primary-expression before ',' token
             hash_map<pair<double, double>, int>g;
                                          ^
0_0_30112968_20540.cpp:95:44: error: expected primary-expression before 'int'
             hash_map<pair<double, double>, int>g;
                                            ^
0_0_30112968_20540.cpp:118:21: error: 'g' was not declared in this scope
                     g[make_pair(a1,a2)]++;
                     ^