#include<stdio.h>
int zhishu(int a) {
	if (a > 2) {
		for (int i = 3; i < a; ) {
			if (a % i == 0) {
					a = 0;
					break;
			}
			i+=2;
		}
		return a;
	}
}
	
	


int huiwen(int a) {
	//先判断几位数
	int i = 1;
	int b = a;
	int c = a;
	while (c >=10) {
		c /= 10;
		i++;
	}
//这个数有i位
	//放进数组
	int arr[9];
	
	for (int j = 0; j < i; j++) {
		arr[j] = b % 10;
		b /= 10;
	}
	if (i % 2 == 0) {
		for (int m = 0; m <= i / 2 && i - m - 1 >=0; m++) {
			if (arr[m] != arr[i - m - 1]) {
				a = 0;
				break;
			}
		}
	}
	else if (i % 2 != 0) {
		for (int m = 0; m <= (i - 1) / 2 && i - m - 1>=0; m++) {
			if (arr[m] != arr[i - m - 1]) {
				a = 0;
				
				break;
			}
		}
	}
	return a;
}
int main() {
	int a, b;
	scanf("%d %d", &a, &b);
	int k;
	if (a < b && a >= 5 && b <= 10e8) {
		for (k = 5; k >= a && k <= b; k+=2) {
				if(huiwen(k)!=0&&zhishu(k)!=0{
					printf("%d\n", k);
				}
		}
	}
	else {
		return 0;
	}
	return 0;
}