#include "bits/stdc++.h" using namespace std; /* macro */ #define rep(i,a,b) for(int i=a;i b; i--) #define int long long #define exist(s,e) ((s).find(e)!=(s).end()) #define all(v) (v).begin(), (v).end() #define each(s,itr) for(auto (itr) = s.begin(); (itr) != s.end(); (itr)++) #define sum(v) accumulate(all(v), (0LL)) #define isin(a, b, c) (b <= a && a <= c) #define println cout << "\n"; #define sz(v) (int)v.size() #define bin(x) static_cast >(x) /* alias */ template using vec = vector; typedef vector vi; typedef pair pi; typedef tuple ti; typedef map mi; typedef set si; /* constant */ const int inf = 1LL << 62; const int mod = 1e9 + 7; const int dx[8]={1,0,-1,0,-1,1,-1,1}; const int dy[8]={0,1,0,-1,-1,-1,1,1}; const string alphabet = "abcdefghijklmnopqrstuvwxyz"; /* io_method */ int input(){int tmp;cin >> tmp;return tmp;} string raw_input(){string tmp;cin >> tmp;return tmp;} template void printx(T n){cout << n;} template void printx(pair p){cout << "(" << p.first << "," << p.second << ")";} template void printx(tuple t){cout << "{" << get<0>(t) << "," << get<1>(t) <<"," << get<2>(t) << "}" << endl;} template void printx(vector v){cout << "{";rep(i,0,v.size()){printx(v[i]);if(i != v.size()-1)printx(",");}cout << "}";} template void print(T n){printx(n);cout << endl;} template void print(set s){cout << "{";each(s, e){if(e != s.begin()) printx(",");printx(*e);}cout << "}" << endl;} template void print(map mp){cout << "{";each(mp, e){cout << "(" << e -> first << "," << e -> second << ")";}cout << "}" << endl;} template void printans(vec v){rep(i,0,sz(v)){cout << v[i] << (i == sz(v) - 1 ? "" : " ");}cout << endl;} /* general_method */ templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (bT cut(T &a, int l, int r){return T(a.begin()+l, a.begin()+r);} /* main */ vector eratothenes(int n){ vector ret; vector isprime(n + 1, true); for(int i = 2; i < sqrt(n + 1) + 1; i++){ if(isprime[i]){ for(int j = 2; i * j < n + 1; j++){ isprime[i * j] = false; } } } for(int i = 2; i < n + 1; i++){ if(isprime[i]) ret.push_back(i); } return ret; } bool is_prime(const unsigned n){ switch(n){ case 0: // fall-through case 1: return false; case 2: // fall-through case 3: return true; } if(n%2 == 0) return false; if(n%3 == 0) return false; if(n%6 != 1 && n%6 != 5) return false; for(unsigned i=5;i*i<=n;i+=6){ if(n%i == 0) return false; // 6n-1 if(n%(i+2) == 0) return false; // 6n+1 } return true; } int n; int k = 0; void in(){ cin >> n; rep(i,0,n) k += (1 << (input() - 1)); } int getbit(int t){ int ret = 0; while(t){ ret |= (1 << ((t % 10) - 1)); t /= 10; } return ret; } void solve(){ vi primes = eratothenes(5000000); int ans = 0; int l = 1; int r = 1; int bits = 0; int cnt = 0; while(l < sz(primes)){ while(r < sz(primes) && ((k | bits) == k)){ if(k == bits){ chmax(ans, primes[r] - 1 - (primes[l - 1] + 1)); } int t = getbit(primes[r]); bits |= t; r++; cnt++; } l = r; cnt = 0; bits = 0; } cout << (ans == 0 ? -1 : ans) << endl; } signed main(){ cin.tie(0); ios::sync_with_stdio(false); in(); solve(); }