pi

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
long double pi(int n) {
    long double sum = 0.0;
    int sign = 1;
    for (int i = 0; i < n; ++i) {
        sum += sign / (2.0*i + 1.0);
        sign *= -1;
    }
    return 4.0*sum;
}
int main()
{
    long double n=1, a=0;
    while (true) {
        cout <<setprecision(1000)<< pi(n)<<endl;
        n++;
        a++;
        /*
        if (a == 5000) {
        system("pause");
        a = 0;
        }*/
    }
    return 0;
}