#include <bits/stdc++.h>
  
using namespace std;
  
#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for(int i=(int)(s-1); i>=(int)(e); i--)
#define pb push_back
#define all(r) r.begin(),r.end()
#define rall(r) r.rbegin(),r.rend()
#define fi first
#define se second
  
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
 
const int INF = 1e9;
const ll MOD = 1e9 + 7;
double EPS = 1e-8;

#define DEBUG_MODE
#ifdef DEBUG_MODE
#define dump(x) cout << #x << " : " << x << endl
#define LINE cout << "line : " << __LINE__ << endl
#define dumpV(v) cout << #v << " : ["; for(auto& t : v) cout << t << ", "; cout<<"]" << endl
#define STOP assert(false)
#else
#define dump(x) ;
#define LINE     ;
#define dumpV(v);
#define STOP     ;
#endif
#define mp make_pair

namespace std{
  template<class S,class T>
  ostream &operator <<(ostream& out,const pair<S,T>& a){
    out<<'('<<a.fi<<", "<<a.se<<')';
    return out;
  }
}


/*
  エラトステネスの篩
  O( n log log n )
  verified yukicoder No. 6
 */
const int MAX_N = 5e6+10;
vector<int> primes;
vector<int> isPrime(MAX_N, 1);
void buildPrimes() {
    isPrime[0] = isPrime[1] = 0;
    REP(i, 2, MAX_N) {
        if(isPrime[i]) {
            primes.push_back(i);
            for(int j = i+i; j < MAX_N; j += i) isPrime[j] = false;
        }
    }
}


int main(){
    buildPrimes();
    int n;
    cin >> n;
    vector<int> v(10);
    rep(i, n) {
        int a;
        cin >> a;
        v[a]++;
    }
    int l = 1, r = 3, ans = -1;
    vector<int> cnt(10, 0);
    cnt[2] = 1;
    constexpr int MAX = 5e6;
    auto check = [&]() {
        rep(i, 10) {
            if(v[i] > 0 && cnt[i] == 0) return 1;
            if(v[i] == 0 && cnt[i] > 0) return -1;
        }
        return 0;
    };
    auto update = [&](int n, bool plus) {
        int x = n;
        while(x > 0) {
            if(plus) cnt[x%10]++;
            else cnt[x%10]--;
            x /= 10;
        }
    };
    while(r <= MAX) {
        // dump(mp(l, r));
        // dumpV(cnt);
        if(check() == 0) ans = max(ans, r - l-1);
        if(check() >= 0) {
            if(isPrime[r]) update(r, true); 
            r++;
        }
        else {
            if(isPrime[l]) update(l, false);
            ++l;
            if(l == r) {
                auto it = lower_bound(all(primes), r);
                if(it == primes.end()) break;
                r = *it;
                update(r, true);
                ++r;
            }
        }
    }
    if(check() == 0) ans = max(ans, r - l-1);
    cout << ans << endl;
    return 0;
}