#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(),x.end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
template<class T> inline bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T&a,T b){if(a>b){a=b;return 1;}return 0;}
using ll = long long;

double a,b,ans,n=1e5;

int main(){
    ios::sync_with_stdio(false); 
    cin.tie(0);
    
   cin >> a >> b;
   rep(i,n){
     double d=(b-a)/n, x=a+(b-a)*i/n;
     ans+=abs((x-a)*(x-b))*d;
   }
   cout << fixed << setprecision(15) << ans << endl;
}