/in/foo.cc: In function 'int main()':
/in/foo.cc:4:14: warning: unused variable 'e' [-Wunused-variable]
  int a,b,c,d,e,f;
              ^
/in/foo.cc:4:16: warning: unused variable 'f' [-Wunused-variable]
  int a,b,c,d,e,f;
                ^