foo.c:4:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^~~~
foo.c: In function 'main':
foo.c:7:7: warning: unused variable 'str3' [-Wunused-variable]
  char str3[100000];
       ^~~~
foo.c:12:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s %s",str1,str2);
  ^~~~~~~~~~~~~~~~~~~~~~~~

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