/* Pi/4 = seira  (-1)^i/(2i+1), i=0,... */
#include <iostream>
#include <cstdlib>
#include <cmath>
#define Max 200
using namespace std;
int main(int argc, char *argv[])
{ int i, N; 
  long double X, ser, A[Max];
  cout<<"Dose plhthos orwn <"<<Max<<": ";
  cin>>N;
  ser=0;      
  for(i=0; i<N; i++)
    {ser=ser+pow(-1.0,i)/(2*i+1); A[i]=ser;}
  cout<<"Athroisma seiras P="<<4*ser<<endl;  
  cout<<"Times ston pinaka gia Pi/4"<<endl;
  cout<<"ektypwsh ana 10 times ston pinaka"<<endl; 
  for(i=0; i<N; i++)
    if ((i+1)%10==0) {cout<<A[i]<<" "; cout << endl;}
  system("Pause");
  return 0;
}