View Compilation Error

0_0_7395912_9913.cpp: In function `int main()':
0_0_7395912_9913.cpp:21: error: `num' undeclared (first use this function)
0_0_7395912_9913.cpp:21: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7395912_9913.cpp:22: error: `nas' undeclared (first use this function)