#include <iostream>
#include <iomanip>
using namespace std;
 
long double PI(size_t count)
  {
   long double prod=1;
   for(size_t i=1;i<=count;++i)
     {
      long double nom=2.0*i,den=nom-1,div=nom/den;
      prod*=div;
      prod*=div;
     }
   return prod/count;
  }
 
int main()
  {
   while(true)
     {
      size_t n;
      cout<<"Podaj parametr funkcji: ";
      if(!(cin>>n)) break;
      cout<<fixed<<setprecision(20)<<PI(n)<<endl;
     }
   return 0;
  }

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MTAwCjEwMDAKMTAwMDAKMTAwMDAwCjEwMDAwMDAKMTAwMDAwMDA=

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