#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
const int INF = 1e9;
const int MOD = 1000000007;

int main(){
    double r,d;
    cin >> r >> d;
    cout << setprecision(20) << pow(d*d - r*r,0.5) << endl;
    return 0;
}