#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
using ll = long long;
using namespace std;
const int INF = 1e9;

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

    printf("%.5f\n", abs(pow(a - b, 3) / 6));

    return 0;
}