#include <iostream> #include <cstdio> #include <string> #include <algorithm> #include <utility> #include <cmath> #include <vector> #include <queue> #include <set> #include <map> #include <numeric> #include <functional> using namespace std; typedef long long ll; typedef vector<ll> vl; typedef vector<vector<ll>> vvl; typedef pair<ll, ll> P; #define rep(i, n) for(ll i = 0; i < n; i++) #define exrep(i, a, b) for(ll i = a; i <= b; i++) #define out(x) cout << x << endl #define exout(x) printf("%.10f\n", x) #define chmax(x, y) x = max(x, y) #define chmin(x, y) x = min(x, y) #define all(a) a.begin(), a.end() #define rall(a) a.rbegin(), a.rend() #define pb push_back #define re0 return 0 const ll mod = 1000000007; const ll INF = 1e16; const ll MAX_N = 100010; int main() { double a, b; cin >> a >> b; double c = b - a; double ans = c*c*c/6.0; exout(ans); re0; }