/in/foo.cc: In function 'int main()':
/in/foo.cc:14:10: error: 'a' was not declared in this scope
   cin >> a[i]; 
          ^
/in/foo.cc:17:10: error: 'b' was not declared in this scope
   cin >> b[i]; 
          ^
/in/foo.cc:26:7: error: 'a' was not declared in this scope
    if(a[i] == b[j])
       ^
/in/foo.cc:26:15: error: 'b' was not declared in this scope
    if(a[i] == b[j])
               ^