#include <bits/stdc++.h>
using namespace std;

int main() {
  int a, b;
  cin >> a >> b;
  double ans = 0;
  for (double i = a; i < b; i += 1.0 * (b - a) / 10000)
    ans += (1.0 * (b - a) / 10000) * abs((i - a) * (i - b));
  cout << fixed << ans << endl;
}