#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, string> pls;

map<char, ll> m;

int main()
{
	for (int i = 0; i < 10; i++)
		m[(char)('0' + i)] = i;

	for (int i = 0; i < 26; i++)
		m[(char('A' + i))] = 10 + i;

	int N;
	cin >> N;
	ll ans = -1;
	for (int i = 0; i < N; i++) {
		string s,s_temp;
		cin >> s;
		s_temp = s;

		sort(s_temp.rbegin(), s_temp.rend());

		int b = m[s_temp[0]] + 1;
		ll num = 0;
		for (int i = 0; i < s.size(); i++)
			num = num * b + m[s[i]];

		if (ans == -1 || ans > num)ans = num;
	}
	cout << ans << endl;
	return 0;
}