#include <bits/stdc++.h>
using namespace std;
#define fx(x) cout<<fixed<<setprecision(x)

int main(){
	double r,d; cin>>r>>d;
	double ang=acos(r/d);
	double ans=r*r+d*d-2*r*d*cos(ang);
	fx(10)<<sqrt(ans)<<endl;
}