#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
typedef int64_t Int;

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

    if(a > b) swap(a,b);

    cout << setprecision(10);
    cout << pow(b-a, 3) / 6.0 << endl;
}