#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<n; ++i)
#define repl(i,m,n) for(ll i=m; i<n; ++i)

bool check(double r, double d, double x){
    return d*d - r*r > x*x;
}

int main(){
    double r, d;
    cin >> r >> d;

    double ok = 0.0, ng = 1e5;
    rep(i, 0, 100){
        double ce = (ok + ng)/2.0;
        if(check(r, d, ce)) ok = ce;
        else ng = ce;
    }
    printf("%.12f\n", ok);
    
    return 0;
}