foo.c: In function 'main':
foo.c:16:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ^~~~~~~~~~~~~~
foo.c:19:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i]);
   ^~~~~~~~~~~~~~~~~
foo.c: In function 'FindMax':
foo.c:11:9: warning: 'max' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return max;
         ^~~
foo.c: In function 'main':
foo.c:6:6: warning: 'max' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int max;
      ^~~

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