#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main(){
	int n1, n2, ans = 0;
	cin >> n1 >> n2;
	for(int i = n1;i <= n2;++i){
		if(i % 4 == 0 || i % 2 == 1){
			ans++;
		}
	}
	cout << ans;
	return 0;
}