View Compilation Error

38741_0_28612.c: In function `main':
38741_0_28612.c:13: error: `num' undeclared (first use in this function)
38741_0_28612.c:13: error: (Each undeclared identifier is reported only once
38741_0_28612.c:13: error: for each function it appears in.)
38741_0_28612.c:13: error: `num2' undeclared (first use in this function)