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:12:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d",&str[i]);
    ^~~~~~~~~~~~~~~~~~~
foo.c:15:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d ",&str[i]);
   ^~~~~~~~~~~~~~~~~~~~
foo.c:45:5: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
  sum+=str[0];
  ~~~^~~~~~~~

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