#include <stdio.h>

int main()
{
	int start = 0, end = 0, min_sweet = 0;
	int temp_num = 0;
	int i = 0;
	scanf("%d %d", &start, &end);

	min_sweet = end + 1;

	for (; start <= end; start++) {
		temp_num = start;
		while (temp_num > 0) {
			if (((temp_num % 10) % 2) != 0) {
				break;
			}
			temp_num /= 10;
		}
		if (temp_num == 0 && start <= min_sweet) {
			min_sweet = start;
		}
	}
	if (min_sweet == end+1) {
		printf("NSN");
	} else {
		printf("%d", min_sweet);
	}
	return 0;
}