#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif

int main() {
    long double a, b;
    cin >> a >> b;

    auto F = [&](long double x) -> long double {
        return x * x * x / 3 - (a + b) / 2 * x * x + a * b * x;
    };

    cout << fixed << setprecision(20) << abs(F(b) - F(a)) << endl;

    return 0;
}