package main

import . "fmt"

func main() {
	var a,b,s float64
	Scan(&a,&b)
	f:=func(x float64) float64 {
		return (x-a)*(x-b)
	}
	const n=1e5
	for x:=1;x<n;x++ {
		s+=(b-a)/n*f((b-a)*float64(x)/n+a)
	}
	Printf("%.8f\n",s)
}