#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>
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
// VAR(int, x);
#define VAR(type, ...)type __VA_ARGS__;Scan(__VA_ARGS__);
template<typename T> void Scan(T& t) { std::cin >> t; }
template<typename First, typename...Rest>void Scan(First& first, Rest&...rest) { std::cin >> first; Scan(rest...); }
#define OUT(d) std::cout<<d;
#define FOUT(n, d) std::cout<<std::fixed<<std::setprecision(n)<<d;
#define SOUT(n, c, d) std::cout<<std::setw(n)<<std::setfill(c)<<d;
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n) for(int i=0;i<int(n);++i)
#define RREP(i, n) for(int i=(n)-1;i>=0;--i)
#define PAIR std::pair<int, int>
#define IN(a, x, b) (a<=x && x<=b)
#define IN2(a0, y, a1, b0, x, b1) (a0<=y && y<a1 && b0<=x && x<b1)
#define SHOW(d) {std::cout << #d << "\t:" << d << "\n";}
#define SHOWVECTOR(v) {std::cout << #v << "\t:";for(const auto& i : v){std::cout << i << " ";}std::cout << "\n";}
#define SHOWVECTOR2(v) {std::cout << #v << "\t:\n";for(const auto& i : v){for(const auto& j : i){std::cout << j << " ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR2(v) {std::cout << #v << "\t:\n";for(const auto& i : v){for(const auto& j : i){std::cout<<'('<<j.first<<", "<<j.second<<") ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR(v) {for(const auto& i:v){std::cout<<'('<<i.first<<", "<<i.second<<") ";}std::cout<<"\n";}
#define CHECKTIME(state) {auto start=std::chrono::system_clock::now();state;auto end=std::chrono::system_clock::now();auto res=std::chrono::duration_cast<std::chrono::nanoseconds>(end-start).count();std::cerr<<"[Time:"<<res<<"ns  ("<<res/(1.0e9)<<"s)]\n";}

//define int ll
using ll = long long;
constexpr int INFINT = 1 << 30;
constexpr ll INFLL = 1LL << 60;
constexpr double EPS = 0.0000001;

int bitUsedNum(int n) {
	int res = 0;
	while (n > 0) {
		res |= 1 << (n % 10);
		n /= 10;
	}
	return res;
} // O( nの桁数 )

std::vector<PAIR> GetPrimeVec(int n) {
	std::vector<bool> num(n, true);
	std::vector<PAIR> prime;
	num[0] = false;
	for (int i = 0; i < std::sqrt(n); ++i) {
		if (num[i]) {
			for (int j = 2; (i + 1)*j <= n; ++j) {
				num[(i + 1)*j - 1] = false;
			}
		}
	}
	for (int i = 0; i < n; ++i) {
		if (num[i]) {
			prime.emplace_back(i + 1, bitUsedNum(i + 1));
		}
	}
	return prime;
} // O( sqrt(n) )

signed main() {
	INIT;
	VAR(int, n);
	int ansBit = 0;
	REP(i, n) {
		VAR(int, a);
		ansBit |= 1 << a;
	}
	auto prime = GetPrimeVec(5000000);
	prime.emplace_back(5000001, 1 << 11);
	int l = 0, r = -1;
	int max = -1;
	int checkBit = 0;
	while (++r < prime.size()) {
		int t = prime[r].second;
		int t2 = t | ansBit;
		if (t2 != ansBit || r + 1 == prime.size()) {
			if (checkBit == ansBit && l != r) {
				int K, L;
				if (l == 0) K = 1;
				else K = prime[l - 1].first + 1;
				L = prime[r].first - 1;

				max = std::max(max, L - K);
			}
			checkBit = 0;
			l = r + 1;
		}
		else {
			checkBit |= t;
		}
	}
	OUT(max)BR;
	return 0;
}