foo.c: In function 'main':
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ^~~~~~~~~~~~~~
foo.c:14:7: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
    sum+=a[i];
    ~~~^~~~~~

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