#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;


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

  double ret = 0;
  double delta = 0.0000001;
  for(double x=a; x<=b; x+=delta){
    double f = -(x-a) * (x-b);
    double area = delta * f;
    ret += area;
  }

  printf("%.12lf\n", ret);
  
  return 0;
}