#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using Graph=vector<vector<pair<int,int>>>;
#define INF 1000000000000000000
#define MOD 1000000007

int main(){
  double a,b;
  cin>>a>>b;
  printf("%lf\n",pow(abs(b-a),3.0)/6.0);
}