foo.c:10:6: warning: return type of 'main' is not 'int' [-Wmain]
   10 | void main()
      |      ^~~~
foo.c: In function 'main':
foo.c:13:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   13 |  scanf("%d%d",&year,&mouth);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~

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