View Compilation Error

0_0_36390336_16687.cpp:34:1: error: 'unordered_map' does not name a type
 unordered_map<long double, int> mp;
 ^
0_0_36390336_16687.cpp: In function 'int main()':
0_0_36390336_16687.cpp:41:9: error: 'mp' was not declared in this scope
         mp.clear();
         ^