foo.c: In function 'main':
foo.c:8:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    8 |  scanf("%d%d",&L,&M);
      |  ^~~~~~~~~~~~~~~~~~~
foo.c:12:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   12 |   scanf("%d%d",&beg,&end);
      |   ^~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务