/in/foo.cc: In function 'int main()':
/in/foo.cc:12:15: warning: 'd1' may be used uninitialized in this function [-Wmaybe-uninitialized]
  sum=(c1+b1+a1+d1)%7654321;
      ~~~~~~~~~^~~~
/in/foo.cc:12:9: warning: 'c1' may be used uninitialized in this function [-Wmaybe-uninitialized]
  sum=(c1+b1+a1+d1)%7654321;
       ~~^~~
/in/foo.cc:12:9: warning: 'b1' may be used uninitialized in this function [-Wmaybe-uninitialized]
/in/foo.cc:12:12: warning: 'a1' may be used uninitialized in this function [-Wmaybe-uninitialized]
  sum=(c1+b1+a1+d1)%7654321;
       ~~~~~^~~