#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<bool> prime(5000001, true);
  prime[0] = false;
  prime[1] = false;
  for (int i = 2; i <= 5000000; i++){
    if (prime[i]){
      for (int j = i * 2; j <= 5000000; j += i){
        prime[j] = false;
      }
    }
  }
  vector<vector<int>> S(5000000);
  for (int i = 1; i <= 5000001; i++){
    if (prime[i]){
      string s = to_string(i);
      for (char c : s){
        S[i - 1].push_back(c - '0');
      }
    }
  }
  vector<int> T(10, 0);
  for (int i = 0; i < N; i++){
    T[A[i]] = 1;
  }
  int ans = -1;
  int R = 0;
  vector<int> cnt(10, 0);
  for (int L = 0; L < 5000000; L++){
    while (R < 5000000){
      vector<int> cnt2 = cnt;
      for (int x : S[R]){
        cnt2[x]++;
      }
      bool ok = true;
      for (int i = 0; i < 10; i++){
        if (T[i] == 0 && cnt2[i] > 0){
          ok = false;
        }
      }
      if (ok){
        swap(cnt, cnt2);
        R++;
      } else {
        break;
      }
    }
    bool ok = true;
    for (int i = 0; i < 10; i++){
      if (T[i] == 1 && cnt[i] == 0){
        ok = false;
      }
    }
    if (ok){
      ans = max(ans, R - L - 1);
    }
    if (R == L){
      R++;
    } else {
      for (int x : S[L]){
        cnt[x]--;
      }
    }
  }
  cout << ans << endl;
}