View Compilation Error

0_0_11954410_18697.cpp: In function `int main(int, const char**)':
0_0_11954410_18697.cpp:9: error: `n' undeclared (first use this function)
0_0_11954410_18697.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11954410_18697.cpp:13: error: `num' undeclared (first use this function)