#include <iostream>
#include <cstdio>

bool prime[10000000];
void primenum(void)
{
	for (int i = 0; i < 10000000; i++){
		prime[i] = true;
		if(i%2==0)prime[i]=false;
	}
	prime[1] = prime[0] = false;
	prime[2]=true;
	for (int i = 3; i*i < 10000000; i+=2){
		for (int j = i * 2; j < 10000000; j += i){
			prime[j] = false;
		}
	}
}

int main(void)
{
	int n;
	primenum();
	while (scanf("%d", &n), n){
		for (int i = n; 0 <= i; i--){
			if (prime[i]&&prime[i-2]&&prime[i-6]&&prime[i-8]){
				printf("%d\n", i);
				break;
			}
		}
	}
	return 0;
}