#include <fstream>

using namespace std;

int v[10];
ifstream fin ("numere.in");
ofstream fout ("numere.out");

void cifra (int n, int &x){

    while (n!=0){
        if (n%10 > x)
            x = n%10;
        n = n/10;
    }
}

int main (){

    int n, x, aux;
    int minim = 10;
    fin >> n;
    for (int i = 1; i <= n; ++i){
        fin >> x;
        int copiex = x;
        while (x){
            aux = 0;
            cifra (x,aux);
            if (x == copiex)
                v[aux]++;
            if (aux != 0 && aux < minim)
                minim = aux;
            x = x/10;
        }
    }

    if (v[0] == n){
        fout << minim;
        for (int i = 1; i < n; ++i)
            fout << 0;
    }
    else {
        bool gasit = 0;
        for (int i = 1; i <= 9 && !gasit; i++)
            if (v[i] != 0){
                fout << i;
                v[i]--;
                gasit = 1;
            }
        for (int i = 0; i <= 9; ++i)
            for (int j = 1; j <= v[i]; ++j)
                fout << i;
    }
}