View Compilation Error

0_0_16237031_27548.c: In function 'main':
0_0_16237031_27548.c:17:3: error: 'sum' undeclared (first use in this function)
   sum=0;
   ^
0_0_16237031_27548.c:17:3: note: each undeclared identifier is reported only once for each function it appears in