#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <stack>
#include <climits>
#include <map>
#include <set>

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

const ll mod = 1000000007;
const int inf = 1e9;
const long long INF = 1LL << 60;


int main()
{
    double a,b;
    cin >> a >> b;
    double ans = (b*b*b - a*a*a)/3.0 - (a+b)*(b*b-a*a)/2.0 + a*b*(b-a);
    cout << abs(ans) << endl;
}