foo.cc: In function 'int main()':
foo.cc:10:10: warning: unused variable 'j' [-Wunused-variable]
  int n,i,j,k,flag,index;
          ^
foo.cc:15:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%s%s%d",&rec[i].id,rec[i].name,rec[i].phone,&rec[i].secs);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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