/in/foo.cc: In function 'int main()':
/in/foo.cc:5:6: warning: variable 'a' set but not used [-Wunused-but-set-variable]
  int a,b,c,d,n,sum1,sum2;
      ^
/in/foo.cc:5:8: warning: variable 'b' set but not used [-Wunused-but-set-variable]
  int a,b,c,d,n,sum1,sum2;
        ^
/in/foo.cc:5:10: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  int a,b,c,d,n,sum1,sum2;
          ^
/in/foo.cc:5:12: warning: variable 'd' set but not used [-Wunused-but-set-variable]
  int a,b,c,d,n,sum1,sum2;
            ^