#include<iostream>
using namespace std;
int main()
{
	int begin,end,k;
	cin >> begin;
	cin >> end;
	cout << (end-begin)/4 << endl;
	for(k=begin;k>=begin&k<=end;k++)
	{
		if(k%4==0&k%100!=0||k%400==0)
		{
			cout << k << "\t";
		}
	}
	return 0;
}