#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 1000000000

double a,b;

double f(double x){
	return pow(x,3)/3.0 - pow(x,2)*(a+b)/2.0 + a*b*x;
}

int main(){
    
	cin>>a>>b;
	
	cout<<fixed<<setprecision(10)<<abs(f(b)-f(a))<<endl;
	
    return 0;
}