foo.c:2:6: warning: return type of 'main' is not 'int' [-Wmain]
    2 | void main()
      |      ^~~~
foo.c: In function 'main':
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d",&a);
      |  ^~~~~~~~~~~~~~
foo.c:12:4: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
   12 |  if(k==b)
      |    ^

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