#include <iostream>
#include <cstring>
#include <vector>
using namespace std;

const int MAX = 5000000;

vector<int> ps;
void sieve(){
    vector<bool> isp(MAX + 10, true);
    
    isp[0] = isp[1] = false;
    for(int p=2;p*p<=MAX;p++)if(isp[p]){
        for(int kp=p*p;kp<=MAX;kp+=p)isp[kp] = false;
    }

    for(int p=2;p<=MAX;p++)if(isp[p])ps.push_back(p);
}

int get_len(int s, int t){
    if(s > t)return -1;
    
    if(s == 0){
        s = 1;
    } else {
        s = ps[s-1] + 1;
    }
    
    if(t == ps.size() - 1){
        t = MAX;
    } else {
        t = ps[t+1] - 1;
    }
    
    return t - s;
}

int solve(int used){
    vector<int> mask(ps.size(), 0);
    for(int i=0;i<ps.size();i++){
        int p = ps[i];
        
        while(p > 0){
            int d = p % 10;
            mask[i] |= 1 << d;
            
            p /= 10;
        }
    }
    
    int res = -1;
    int start = 0;
    int acc = 0;
    for(int i=0;i<ps.size();i++){
        if(mask[i] & (~used)){
            if(acc == used){
                res = max(res, get_len(start, i - 1));
            }
            start = i + 1;
            acc = 0;
        } else {
            acc |= mask[i];
        }
    }
    
    if(acc == used){
        res = max(res, get_len(start, (int)ps.size() - 1));
    }
    
    return res;
}

int main(){
    sieve();
    
    int N;
    cin >> N;
    
    int used = 0;
    for(int i=0;i<N;i++){
        int d;
        cin >> d;
        
        used |= 1 << d;
    }
    
    cout << solve(used) << endl;
    return 0;
}