/in/foo.cc: In function 'int main()':
/in/foo.cc:13:11: warning: unused variable 'k' [-Wunused-variable]
  long i,j,k,a,b,c,n;
           ^
/in/foo.cc:13:17: warning: unused variable 'c' [-Wunused-variable]
  long i,j,k,a,b,c,n;
                 ^