//	computes the KS statistic given the sample count, N, and the maximum difference, d

#include <iostream>
#include <math.h>
#include <fstream>
#include <iomanip>

using namespace std;

double x,d,p;
int N;


int main()
{
	cout << "N=";
	cin >> N;
	cout << "diff=";
	cin >> d;
	
	x = d*(sqrt(N)+0.12+0.11/sqrt(N));
	p = 0;
	
	for (int i=1; i<(N*1000); i++) {
		p += pow(-1,(i - 1)) * exp(-2 * pow(i,2.0) * pow(x,2.0));
	}
	p = 2*p;
	cout << "P=" << p << endl;
	return 0;
}