foo.cc: In function 'int main()':
foo.cc:5:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    5 |  freopen("out.txt","w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    7 |  scanf("%d,%d",&n,&k);
      |  ~~~~~^~~~~~~~~~~~~~~

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