View Compilation Error

0_0_22863213_2087.c: In function 'main':
0_0_22863213_2087.c:15:2: error: 'sum' undeclared (first use in this function)
  sum=0;
  ^
0_0_22863213_2087.c:15:2: note: each undeclared identifier is reported only once for each function it appears in