View Compilation Error

1090970_0_0_4235.cpp: In function `int main()':
1090970_0_0_4235.cpp:7: error: `string' undeclared (first use this function)
1090970_0_0_4235.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
1090970_0_0_4235.cpp:7: error: expected `;' before "s"
1090970_0_0_4235.cpp:9: error: expected `;' before "op"
1090970_0_0_4235.cpp:10: error: `cin' undeclared (first use this function)
1090970_0_0_4235.cpp:10: error: `s' undeclared (first use this function)
1090970_0_0_4235.cpp:27: error: `cout' undeclared (first use this function)
1090970_0_0_4235.cpp:27: error: `op' undeclared (first use this function)
1090970_0_0_4235.cpp:30: error: `endl' undeclared (first use this function)