View Compilation Error

0_0_7253497_31739.cpp:4: error: expected unqualified-id before numeric constant
0_0_7253497_31739.cpp:4: error: expected `,' or `;' before numeric constant
0_0_7253497_31739.cpp: In function `double stirling(int)':
0_0_7253497_31739.cpp:7: error: `pi' undeclared (first use this function)
0_0_7253497_31739.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7253497_31739.cpp:7: error: `e' undeclared (first use this function)
0_0_7253497_31739.cpp: In function `int main()':
0_0_7253497_31739.cpp:12: error: `cin' undeclared (first use this function)
0_0_7253497_31739.cpp:16: error: `cout' undeclared (first use this function)
0_0_7253497_31739.cpp:16: error: `endl' undeclared (first use this function)
0_0_7253497_31739.cpp:18: error: `system' undeclared (first use this function)