foo.c: In function 'main':
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    6 |  scanf("%d",&n);
      |  ^~~~~~~~~~~~~~
foo.c:7:2: warning: 'i' is used uninitialized in this function [-Wuninitialized]
    7 |  for(l=2;l<i;l++)
      |  ^~~

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