View Compilation Error

0_0_18504641_17069.cpp: In function 'int main()':
0_0_18504641_17069.cpp:7:7: error: 'a' was not declared in this scope
   for(a=0;a<n;a++)
       ^
0_0_18504641_17069.cpp:10:16: error: 'b' was not declared in this scope
    scanf("%d",&b);
                ^
0_0_18504641_17069.cpp:14:9: error: 'sun' was not declared in this scope
     sum=sun+d;
         ^