#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
using namespace std;
using ll = long long;
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; }
const ll INF = 1e9;
const ll MOD = 1e9 + 7;


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

    auto f = [&](long double x){
        return - (x - a) * (x - b);
    };

    long double ans = 0;

    long double x = a;
    long double diff = 1e-6;
    while(x <= b){
        ans += f(x) * diff;
        x += diff;
    }

    cout << fixed << setprecision(9) << ans << endl;
}