View Compilation Error

0_0_31371970_14679.cpp: In function 'int main()':
0_0_31371970_14679.cpp:13:9: error: 'a' was not declared in this scope
    cin>>a[i];
         ^
0_0_31371970_14679.cpp:14:9: error: expected ';' before 'a'
    sum++a[i];
         ^