View Compilation Error

0_0_14191002_21834.cpp:13:1: error: 'unordered_map' does not name a type
 unordered_map<int,int>ma;
 ^
0_0_14191002_21834.cpp: In function 'bool isfind()':
0_0_14191002_21834.cpp:18:12: error: 'ma' was not declared in this scope
         if(ma.count(n - num[i]))
            ^
0_0_14191002_21834.cpp: In function 'int solve()':
0_0_14191002_21834.cpp:25:8: error: 'ma' was not declared in this scope
     if(ma.count(n))return 1;
        ^
0_0_14191002_21834.cpp: In function 'int main()':
0_0_14191002_21834.cpp:36:9: error: 'ma' was not declared in this scope
         ma[num[cnt]] = 1;
         ^