foo.c: In function 'main':
foo.c:29:3: warning: statement with no effect [-Wunused-value]
   for (start; start < end + 1; start++)
   ^~~
foo.c:15:7: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  Koop:scanf("%d%d", &L, &M);
       ^~~~~~~~~~~~~~~~~~~~~
foo.c:23:8: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   Loop:scanf("%d%d", &start, &end);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务