// includes
#include <cstdio>
#include <cstdint>
#include <iostream>
#include <iomanip>
#include <string>
#include <queue>
#include <stack>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <utility>
#include <functional>
#include <cmath>
#include <climits>
#include <bitset>
#include <list>
#include <random>

// macros
#define ll long long int
#define pb emplace_back
#define mk make_pair
#define pq priority_queue
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())

using namespace std;

//  types
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
typedef pair<double, double> Pd;
 
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1e9 + 7;

// solve
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}

template <typename T>
vector<T> list_prime(T n){
  vector<T> res;
  vector<bool> i_prime = vector<bool>(n+1, true);
  for(ll i = 2; i <= n; i++){
    if(i_prime[i]){
      res.push_back(i);
      for(ll j = 2; j * i <= n; j++){
        i_prime[i * j] = false;
      }
    }
  }
  return res;
}

int main(int argc, char const* argv[])
{
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> a(n);
  vector<bool> b(10, false);
  rep(i, n){
    cin >> a[i];
    b[a[i]] = true;
  }
  auto p = list_prime(5000000);
  vector<int> v;
  for(int i = 0; i < sz(p); i++){
    int tmp = p[i];
    while(tmp){
      if(!b[tmp % 10]){
        v.pb(i);
        break;
      }
      tmp /= 10;
    }
  }
  if(sz(v) == 0){
    cout << 4999999 << endl;
    return 0;
  }
  int res = -1;
  for(int i = 0; i < sz(v) - 1; i++){
    vector<bool> used(10, false);
    bool flag = false;
    for(int j = v[i]+1; j < v[i+1]; j++){
      flag = true;
      int tmp = p[j];
      while(tmp){
        used[tmp % 10] = true;
        tmp /= 10;
      }
    }
    for(int j = 0; j < n; j++)flag = flag & (used[a[j]]);
    if(flag)res = max(res, p[v[i+1]] - p[v[i]] - 2);
  }
  vector<bool> used(10, false);
  bool flag = false;
  for(int i = 0; i < v[0]; i++){
    flag = true;
    int tmp = p[i];
    while(tmp){
      used[tmp % 10] = true;
      tmp /= 10;
    }
  }
  for(int i = 0; i < 10; i++){
    flag = flag & ((b[i] && used[i]) || (!b[i] && !used[i]));
  }
  if(flag)res = max(res, p[v[0]] - 2);
  used.assign(10, false);
  flag = false;
  for(int i = v[sz(v)-1] + 1; i < sz(p); i++){
    flag = true;
    int tmp = p[i];
    while(tmp){
      used[tmp % 10] = true;
      tmp /= 10;
    }
  }
  for(int i = 0; i < 10; i++){
    flag = flag & ((b[i] && used[i]) || (!b[i] && !used[i]));
  }
  if(flag)res = max(res, 5000000 - p[v[sz(v)-1]]);
  cout << res << endl;
	return 0;
}