View Compilation Error

0_0_4000827_29515.cpp:1: error: `string' does not name a type
0_0_4000827_29515.cpp: In function `int main()':
0_0_4000827_29515.cpp:21: error: `string' undeclared (first use this function)
0_0_4000827_29515.cpp:21: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4000827_29515.cpp:21: error: expected `;' before "f"
0_0_4000827_29515.cpp:22: error: `f' undeclared (first use this function)
0_0_4000827_29515.cpp:26: error: `add' undeclared (first use this function)
0_0_4000827_29515.cpp:27: error: `cin' undeclared (first use this function)
0_0_4000827_29515.cpp:28: error: `cout' undeclared (first use this function)
0_0_4000827_29515.cpp:28: error: `endl' undeclared (first use this function)