B. Water Lily【1000 / 计算几何】

https://codeforces.com/problemset/problem/1199/B

#include<bits/stdc++.h>
using namespace std;
int main(void)
{
	double h,l; cin>>h>>l;
	printf("%.13lf",(l*l-h*h)/2/h);
	return 0;
}