#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cctype>
#include <string>
#include <cstring>

using namespace std;

char getBiggestChar(string &s) {
	char ret = s[0];
	for (int i = 0; i < s.size(); i++) {
		for (int j = 0; j < s.size(); j++) {
			if (s[j] > ret) {
				ret = s[j];
			}
		}
	}
	return ret;
}

bool isNumber(char c) {
	return c <= '9';
}

int toNumber(char c) {
	int ret = (int)c;
	if (isNumber(c)) {
		ret -= '0';
	} else {
		ret -= 'A' - 10;
	}
	return ret;
}

int toBase(char c) {
	return toNumber(c) + 1;
}

long long encode(string s, int b) {
	long long ret = 0;
	long long mul = 1;
	for (int i = 0; i < s.size(); i++) {
		int num = toNumber(s[s.size() - 1 - i]);
		ret += num * mul;
		mul *= b;
	}
	return ret;
}

int main(void) {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	int N;
	cin >> N;
	vector<string> V;
	for (int i = 0; i < N; i++) {
		string s;
		cin >> s;
		V.push_back(s);
	}
	long long min = -1;
	for (int i = 0; i < V.size(); i++) {
		int base = toBase(getBiggestChar(V[i]));
		long long encoded = encode(V[i], base);
		if ((encoded < min) || (min == -1)) {
			min = encoded;
		}
	}
	cout << min << endl;
}