View Compilation Error

0_0_6539403_25233.cpp:13:25: unordered_map: No such file or directory
0_0_6539403_25233.cpp:14: error: `std::unordered_map' has not been declared
0_0_6539403_25233.cpp:38: error: expected constructor, destructor, or type conversion before '<' token
0_0_6539403_25233.cpp:38: error: expected `,' or `;' before '<' token
0_0_6539403_25233.cpp: In function `int main()':
0_0_6539403_25233.cpp:65: error: `front' undeclared (first use this function)
0_0_6539403_25233.cpp:65: error: (Each undeclared identifier is reported only once for each function it appears in.)