View Compilation Error

0_0_2555801_11095.cpp: In function `int main()':
0_0_2555801_11095.cpp:11: error: `n' undeclared (first use this function)
0_0_2555801_11095.cpp:11: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_2555801_11095.cpp:11: error: `f' undeclared (first use this function)