foo.cc: In function 'int main()':
foo.cc:47:20: warning: format '%lf' expects argument of type 'double', but argument 2 has type 'long double' [-Wformat=]
  printf("%.2lf",mid);
                    ^
foo.cc:36:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
foo.cc:38:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d",&x[i],&y[i],&s[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务