#include <iostream>
#include <iomanip>
#include <unistd.h>

using namespace std;

const long long WORK_SIZE {10'000'000'000};

int main() {

     long double finalPi{4};
     int sign{-1};

     cout << "My pid is " << getpid() << endl;

     for(long long  i = 3; i < WORK_SIZE; i += 2) {
         finalPi += sign * 4 /static_cast<long double> (i);
         sign *= -1;
     }

     cout << "PI = "  << setprecision(20) << finalPi << endl;
     return 0;
}