#include <bits/stdc++.h>
using namespace std;
using i64 = int64_t;
using vi = vector<i64>;
using vvi = vector<vi>;

const int nax = 5000001;

vi ps;

int main() {
    ps = vi(nax, 1);
    ps[0] = ps[1] = 0;
    for (int i = 2; i < nax; i++) {
        if (!ps[i]) continue;
        for (int j = 2; i * j < nax; j++) {
            ps[i * j] = 0;
        }
    }

    vi qs;
    for (int i = 0; i < nax; i++) {
        if (ps[i]) qs.push_back(i);
    }

    int n;
    cin >> n;
    set<int> use;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;
        use.insert(a);
    }
    set<int> ss;

    int l = 0, r = 0;
    i64 width = -1;
    while (1) {
        if (use != ss) {
            if (r == qs.size()) break;
            int q = qs[r];
            int ok = 1;
            while (q) {
                if (use.count(q % 10) == 0) {
                    ok = 0;
                }
                q /= 10;
            }
            if (ok) {
                q = qs[r];
                while (q) {
                    ss.insert(q % 10);
                    q /= 10;
                }
                if (use == ss) {
                    width = max(width, ((r + 1 == qs.size() ? nax : qs[r + 1]) - 1) - ((l == 0 ? 0 : qs[l - 1]) + 1));
                }
                r++;
            } else {
                l = r + 1;
                r = l;
                ss.clear();
            }
        } else {
            if (r == qs.size()) break;
            int q = qs[r];
            int ok = 1;
            while (q) {
                if (use.count(q % 10) == 0) {
                    ok = 0;
                }
                q /= 10;
            }
            if (ok) {
                width = max(width, ((r + 1 == qs.size() ? nax : qs[r + 1]) - 1) - ((l == 0 ? 0 : qs[l - 1]) + 1));
                r++;
            } else {
                l = r + 1;
                r = l;
                ss.clear();
            }      
        }    
    }
    cout << width << endl;
}