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

const ll mod = ll(1e9) + 7;
const int INF = 1<<29;

int main(){
    int a,b;
    cin >> a >> b;
    double ans = 0.0;
    for (double i=a;i<b;i+=0.1){
        ans += 0.1*abs((i-a)*(i-b));
    }
    cout << ans << endl;
    return 0;
}