View Compilation Error

0_0_27522984_5666.cpp: In function 'int main()':
0_0_27522984_5666.cpp:6:2: error: expected initializer before 'scanf'
  scanf("%d",&n);
  ^
0_0_27522984_5666.cpp:12:15: error: 'a' was not declared in this scope
    scanf("%d",a[i]);
               ^
0_0_27522984_5666.cpp:17:10: error: 'a' was not declared in this scope
     sum+=a[j];
          ^