#include<bits/stdc++.h>
using namespace std;
bool is_leap_year(int);
int main()
{
	int left,right;
	long long sum=0;
	cin>>left>>right;
	for(int year=left;year<=right;year++)
	{
		if(is_leap_year(year)==true)
		{
			sum+=year;
		}
	}
	cout<<sum;
	return 0;
}
bool is_leap_year(int year)
{
	if(year%4!=0)
	{
		return false;
	}
	else
	{
		if(year%100==0)
		{
			if(year%400==0)
			{
				return true;
			}
			else
			{
				return false;
			}
		}
		else
		{
			return true;
		}
	}
}