View Compilation Error

0_0_4230503_18886.cpp: In function `int main()':
0_0_4230503_18886.cpp:10: error: `n' undeclared (first use this function)
0_0_4230503_18886.cpp:10: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4230503_18886.cpp:14: error: `j' undeclared (first use this function)
0_0_4230503_18886.cpp:16: error: `i' undeclared (first use this function)
0_0_4230503_18886.cpp:20: error: `num' undeclared (first use this function)