#include "bits/stdc++.h"
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;

typedef long long ll;

int main() {
    double a, b;
    cin >> a >> b;
    double ans = (b * b * b - a * a * a) / 3 - (a + b) * (b * b - a * a) / 2 + a * b * (b - a);
    cout << setprecision(10) << abs(ans) << "\n";
}