#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
#include <bitset>
#include <stack>
#include <assert.h>
#include <unordered_set>
#include <random>


using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll INF = 1e18;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(ll i = 0; i < n; i++)













 
int main(){
    double a, b;
    scanf("%lf %lf", &a, &b);
    double s = 0, n = 100000.0;
    for(double i = 1.0; i <= n; i += 1.0){
        s += (b - a) / n * abs((a + (b - a) / n * i - a) * (a + (b - a) / n * i - b));
    }
    printf("%.6lf\n", s);
}