foo.cc: In function 'int main()':
foo.cc:12:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   12 | freopen("p1345.in","r",stdin);
      | ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:13:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 | scanf("%d",&n);
      | ~~~~~^~~~~~~~~
foo.cc:18:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   18 | scanf("%s",s);
      | ~~~~~^~~~~~~~

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