foo.c: In function 'main':
foo.c:12:8: warning: unused variable 'e' [-Wunused-variable]
  int k,e;
        ^
foo.c:12:6: warning: unused variable 'k' [-Wunused-variable]
  int k,e;
      ^
foo.c:14:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ^~~~~~~~~~~~~~
foo.c:17:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&a[i].left,&a[i].right);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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