using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;
using System.IO;

class Program
{
    static private Magatro M = new Magatro();
    static private void Main(string[]args)
    {
        M.Scan();
        M.Solve();
    }
}

public class Scanner
{
    private string[] S;
    private int Index;
    private char Separator;

    public Scanner(char separator = ' ')
    {
        Index = 0;
        Separator = separator;
    }

    private string[] Line()
    {
        return Console.ReadLine().Split(Separator);
    }

    public string Next()
    {
        string result;
        if (S == null || Index >= S.Length)
        {
            S = Line();
            Index = 0;
        }
        result = S[Index];
        Index++;
        return result;
    }
    public int NextInt()
    {
        return int.Parse(Next());
    }
    public double NextDouble()
    {
        return double.Parse(Next());
    }
    public long NextLong()
    {
        return long.Parse(Next());
    }
}

public class Magatro
{
    private Scanner Sc = new Scanner();
    private int N;
    private Dictionary<char, long> Dic = new Dictionary<char, long>();
    private const string Num = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    public void Scan()
    {
        N = Sc.NextInt();
    }

    private void Start()
    {
        for(int i = 0; i < Num.Length; i++)
        {
            Dic.Add(Num[i], i);
        }
    } 

    public void Solve()
    {
        Start();
        long ans = long.MaxValue;
        for(int i = 0; i < N; i++)
        {
            string v = Sc.Next();
            ans = Math.Min(ans, Converter(v));
        }
        Console.WriteLine(ans);
    }

    private long Converter(string s)
    {
        long result = 0;
        int length = s.Length;
        long ary = -1;
        for(int i = 0; i < length; i++)
        {
            ary = Math.Max(ary, Dic[s[i]] + 1);
        }
        for (int i = 0; i < length; i++)
        {
            int digit = length - i - 1;
            result += Dic[s[i]] * MyPow(ary, digit);
        }
        return result;
    }

    private long MyPow(long a,int b)
    {
        long cpa = a;
        long result = 1;
        while (b > 0)
        {
            if (b % 2 == 0)
            {
                cpa *= cpa;
                b /= 2;
            }
            else
            {
                result *= cpa;
                b--;
            }
        }
        return result;
    }
}