foo.cc: In function 'int main()':
foo.cc:14:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  freopen("P1310_2.in","r",stdin);
  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:15:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
foo.cc:16:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",s+1);
  ~~~~~^~~~~~~~~~

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