#include<stdio.h>
#include<stdbool.h>
bool SelectYear(int x){
	if(x % 100 != 0 && x % 4 == 0 || x % 400 == 0){
		return true;
	}
	return false;
}
int main(){
	int x,y;
	int i = 0;
	int a[2000];
	scanf("%d %d",&x,&y);
//	bool s = SelectYear(x);
	while(x < y){
		if(SelectYear(x)){
			a[i] = x;
			i++;
		}
		x++;		
	}
	printf("%d\n",i);
	for(int j = 0; j < i; j++){
		printf("%d ",a[j]);
	}
	return 0;
}