#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int get(vector<int> &c){
	int ret = 0;
	rep(i,10){
		if(c[i]>0)ret |= 1<<i;
	}
	return ret;
}

int main(){
	
	vector<bool> f(5000001,true);
	f[0] = false;
	f[1] = false;
	for(int i=2;i<f.size();i++){
		if(!f[i])continue;
		for(int j=i*2;j<f.size();j+=i)f[j] = false;
	}
	
	vector<int> t(f.size(),0);
	
	rep(i,f.size()){
		if(f[i]){
			int x = i;
			while(x!=0){
				t[i] |= 1<<(x%10);
				x/=10;
			}
		}
	}
	
	int N;
	cin>>N;
	
	int tt = 0;
	rep(i,N){
		int x;
		cin>>x;
		tt |= 1<<x;
	}
	
	int ans = -1;
	
	vector<int> cnt(10,0);
	int l = 1;
	for(int i=1;i<f.size();i++){
		if(f[i]){
			rep(j,10){
				if((t[i]>>j)&1)cnt[j]++;
			}
		}
		while((get(cnt)|tt)!=tt){
			if(f[l]){
				rep(j,10){
					if((t[l]>>j)&1)cnt[j]--;
				}
			}
			l++;
		}
		if(get(cnt)==tt)ans = max(ans,i-l);
	}
	if(ans==0)ans = -1;
	cout<<ans<<endl;
	
	return 0;
}