#include <gsl/gsl_cdf.h>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int x = 2133;
    int n = 10000;
    cout << gsl_cdf_beta_P(gsl_cdf_beta_Pinv(0.025, x, n - x + 1), x, n - x + 1) << endl;
    return 0;
}