#include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef long long ll;
typedef pair<int,int> P;
int main()
{
  long N = pow(10, 3);
  int a, b;
  cin >> a >> b;
  double S = 0;
  double div = (b - a) / N;
  for (int i = 0; i < N;i++)
  {
    double x = a + i * div;
    S += (x - a) * (x - b) / N;
  }
  cout << fixed <<S << endl;
}