foo.cc: In function 'int main()':
foo.cc:12:6: warning: statement has no effect [-Wunused-value]
 for(m; s1[m]!=0; m++) ;
      ^
foo.cc:13:6: warning: statement has no effect [-Wunused-value]
 for(k; s2[k]!=0; k++) ;
      ^
foo.cc:9:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%s",s1);
 ~~~~~^~~~~~~~~
foo.cc:10:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%s",s2);
 ~~~~~^~~~~~~~~

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