#include <iostream>
#include <stdio.h>
#include <math.h>
using namespace std;
int main(int argc, char* argv[])
{
	double r,d;
	cin>>r>>d;
	double L2=d*d-r*r;
	double L=sqrt(L2);
	printf("%.12f\n",L);
	return 0;
}