foo.cc: In function 'int main()':
foo.cc:5:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d\n",&raws,&lines);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:8:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
       scanf("%d ",&n);
       ~~~~~^~~~~~~~~~
foo.cc:11:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("\n");
     ~~~~~^~~~~~

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