foo.c: In function 'main':
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&a);
  ^~~~~~~~~~~~~~
foo.c:9:8: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   b = b*10 +a%10;
       ~^~~

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