/in/foo.cc: In function 'int main()':
/in/foo.cc:17:6: warning: unused variable 'i' [-Wunused-variable]
  int i, cas, n, a, b, k;
      ^
/in/foo.cc:17:14: warning: unused variable 'n' [-Wunused-variable]
  int i, cas, n, a, b, k;
              ^