/in/foo.cc: In function 'int main()':
/in/foo.cc:15:10: warning: unused variable 'j' [-Wunused-variable]
  int n,i,j,k;
          ^
/in/foo.cc:15:12: warning: unused variable 'k' [-Wunused-variable]
  int n,i,j,k;
            ^