#include<iostream>
#include<algorithm>
#include<string>
#include<math.h>
#include<bitset>
#include <vector>
#include<bitset>
#include <iomanip>
#include <map>
#include <set>
#include <stack>
#include <deque>
#include <climits>
#include <queue>
using namespace std;


int main() {
	
	double D, R;
	cin >> R >> D;
	double answer = D * D - R * R;
	printf("%.10f\n", pow(answer,0.5));



	
}