foo.c: In function 'main':
foo.c:20:11: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long int' [-Wformat=]
  printf("%d\n",sum);
          ~^
          %ld
foo.c:7:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%ld %d",&ran,&num);
  ^~~~~~~~~~~~~~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。