#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <set>
#include <algorithm>
#define _USE_MATH_DEFINENS
#include <cmath>
using namespace std;

#define p(x) cout << x << endl;
#define el cout << endl;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    double r, d;
    cin >> r >> d;
    double ans = (d * d) - (r * r);
    ans = sqrt(ans);
    cout << ans << endl;
}