#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

using namespace std;

#define all(c) ((c).begin()), ((c).end())
#define dump(c) cerr << "> " << #c << " = " << (c) << endl;
#define iter(c) __typeof((c).begin())
#define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++)
#define REP(i, a, b) for (int i = a; i < (int)(b); i++)
#define rep(i, n) REP(i, 0, n)
#define mp make_pair
#define fst first
#define snd second
#define pb push_back
#define debug(fmt, ...) \
        fprintf( stderr, \
                  fmt "\n", \
                  ##__VA_ARGS__ \
        )

typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int INF = 1 << 29;
const double EPS = 1e-10;

double zero(double d) {
    return d < EPS ? 0.0 : d;
}

template<class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
bool chmin(T &a, const T &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}

#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    return os << '(' << p.first << ',' << p.second << ')';
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &a) {
    os << '[';
    rep(i, a.size()) os << (i ? " " : "") << a[i];
    return os << ']';
}

string toString(int i) {
    stringstream ss;
    ss << i;
    return ss.str();
}

const int MOD = 1000000007;

// a^k
ll fpow(ll a, ll k, int M) {
    ll res = 1ll;
    ll x = a;
    while (k != 0) {
        if ((k & 1) == 1)
            res = (res * x) % M;
        x = (x * x) % M;
        k >>= 1;
    }
    return res;
}

struct prepare {
    prepare() {
        cout.setf(ios::fixed, ios::floatfield);
        cout.precision(8);
        ios_base::sync_with_stdio(false);
    }
} _prepare;


const int MAX_N = 5 * (int) (1e6) + 2;
vector<vector<bool> > used(MAX_N, vector<bool>(10, false));
vi A(10, 0);

bool checker(vi &now) {
    rep(i, 10) {
        if(now[i] != 0 && A[i] == 0)
            return false;
    }
    return true;
}
bool strict_checker(vi &now) {
    rep(i, 10) {
        if( (now[i] != 0 && A[i] == 0) ||
            (now[i] == 0 && A[i] != 0) )
            return false;
    }
    return true;
}

int main() {
    int N;
    cin >> N;

    rep(i, N) {
        int t;
        cin >> t;
        A[t]++;
    }

    vector<bool> sieve(MAX_N, true);
    sieve[0] = sieve[1] = false;

    REP(i, 2, MAX_N) {
        for (int j = 2 * i; j < MAX_N; j += i) {
            sieve[j] = false;
        }
    }

    REP(i, 1, MAX_N) {
        if (sieve[i]) {
            if (sieve[i]) {
                int tmp = i;
                while (tmp > 0) {
                    int t = tmp % 10;
                    used[i][t] = true;
                    tmp /= 10;
                }
            }
        }
    }

    int ans = -1;
    vi now(10, 0);
    for (int l = 1, r = 1;; l++) {
        for (;r < MAX_N-1;) {
            if(!checker(now))
                break;
            else
                r++;
            rep(i, 10)
                now[i] += used[r][i];
        }

        // はみ出しチェック
        if(checker(now)) {
            // 一つ戻してチェック
            rep(i, 10)
                now[i] -= used[r][i];
            if(strict_checker(now))
                chmax(ans, r-l-1);
            break;
        }

        // 一つ戻してチェック
        rep(i, 10)
            now[i] -= used[r][i];
        if(strict_checker(now))
            chmax(ans, r - l - 1);
        rep(i, 10)
            now[i] += used[r][i];

        rep(i, 10)
            now[i] -= used[l][i];
    }

    cout << ans << endl;

    return 0;
}