#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

void findPrime(int N, vector<bool>& isPrime)
{
    isPrime.assign(N+1, true);
    isPrime[0] = isPrime[1] = false;
    for(int i=2; i*i<=N; i++){
        if(isPrime[i]){
            for(int j=i; i*j<=N; j++){
                isPrime[i*j] = false;
            }
        }
    }
}

void addCnt(int x, vector<int>& cnt)
{
    ostringstream oss;
    oss << x;
    string s = oss.str();
    for(unsigned i=0; i<s.size(); ++i)
        ++ cnt[s[i]-'0'];
}
void subCnt(int x, vector<int>& cnt)
{
    ostringstream oss;
    oss << x;
    string s = oss.str();
    for(unsigned i=0; i<s.size(); ++i)
        -- cnt[s[i]-'0'];
}

int main()
{
    vector<bool> isPrime;
    findPrime(5000000, isPrime);

    int n;
    cin >> n;
    bitset<10> select;
    for(int i=0; i<n; ++i){
        int a;
        cin >> a;
        select[a] = true;
    }

    int left = 1;
    int right = 0;
    int ret = -1;
    vector<int> cnt(10, 0);
    for(;;){
        bool isNeedAdd = false;
        bool isNeedSub = false;
        for(int i=0; i<10; ++i){
            if(select[i] && cnt[i] == 0)
                isNeedAdd = true;
            if(!select[i] && cnt[i] > 0)
                isNeedSub = true;
        }

        if(!isNeedAdd && !isNeedSub){
            ret = max(ret, right - left);
        }

        if(isNeedSub){
            if(isPrime[left])
                subCnt(left, cnt);
            ++ left;
        }
        else{
            ++ right;
            if(right > 5000000)
                break;
            if(isPrime[right])
                addCnt(right, cnt);
        }
    }
    cout << ret << endl;

    return 0;
}