#include <iostream>
#include <math.h>
#define cmp(a, b) (a += b, b = a - b, a -= b)
using namespace std;

double f(int a, int b, double x){
    return -(x - a) * (x - b);
}

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

    if (a > b) cmp(a, b);
    int n = abs(b - a) * 10000;
    double ans = 0.0;

    for(double i = a; i < b; i += 0.0001){
        ans += (double)(b - a) / (double)n * f(a, b, i);
    }
    cout << ans << endl; 

    return 0;
}