foo.c: In function 'main':
foo.c:22:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ^~~~~~~~~~~~~~~~~~~
foo.c:24:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   (void)scanf("%d",&v[i]);
   ^~~~~~~~~~~~~~~~~~~~~~~
foo.c:27:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   (void)scanf("%d",&plus);
   ^~~~~~~~~~~~~~~~~~~~~~~
foo.c:29:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    (void)scanf("%d",&cost[j]);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~