foo.cc: In function 'int main()':
foo.cc:23:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  freopen("sjs.txt","r",stdin);
  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
foo.cc:26:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&cnt);
   ~~~~~^~~~~~~~~~~
foo.cc:30:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d",&Ja[i].str);
    ~~~~~^~~~~~~~~~~~~~~~~

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