#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    vector<int> a(n);
    for(int i = 0;i<n;i++) cin>>a[i];
    
    vector<int> cnt(10,-1);
    for(int i = 0;i<n;i++) cnt[a[i]]=0;

    int R = 5e6;
    int L = 1;
    vector<int> p(R+1,-1);
    p[0] = 1;
    p[1] = 1;
    for(int i = 2;i<=R;i++){
        if(p[i]==1) continue;
        p[i] = 0;
        for(int j = i + i;j<=R;j+=i)p[j]=1;
    }
    int ans = -1;
    int cc = 0;
    int l = 1,r = 1;
    while(l<=R&&r<=R){
        //cout<<l<<" "<<r<<endl;  
        if(p[r]){
            r++;
            continue;
        }
        //cout<<r<<endl;
        bool q = true;
        int m = r;
        while(m){
            int now = m % 10;
            m /= 10;
            if(cnt[now]==-1) q = false;
            else cnt[now]++;
        }
        if(q){
            cc++;
            r++;
            continue;
        }
        if(cc==0){
            l = r = r + 1;
            continue;
        }
        cc = 0;
        int now = r - 1 - l;
        q = true;
        for(int i = 0;i<n;i++){
            if(cnt[a[i]]==0) q = false;
            cnt[a[i]] = 0;
        }
        if(q) ans = max(ans,now);
        //cout<<ans<<" "<<l<<" "<<r<<endl;
        l = r = r + 1;
    }
    bool q = true;
    for(int i = 0;i<n;i++){
        if(cnt[a[i]] == 0) q = false;
    }
    if(q) ans = max(ans,R-l);
    cout<<ans<<endl;    

}