#include "omp.h"
#include <stdio.h>

int main(void) {

    double pi = 0;
    #pragma omp parallel
    {
        int i = 0;
        #pragma omp parallel for
        for (i = 0; i < 1000000000; i += 1) {
            int sign = (i % 2) ? -1 : 1,
                denom = (1 + (i * 2)) * sign;
            pi += 4.0 / denom;
        }
    }
    printf("%.91f\n", pi);
}