import java.io.*;
import java.util.*;

class Main {
	
	public static void out (Object o) {
		System.out.println(o);
	}
	
	public static long getDecimal (String v) {
		long ret = 0;
		String s = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		
		int max = 0;
		for (int i = 0; i < v.length(); i++) {
			max = Math.max(max , (int)v.charAt(i));
		}
		
		long k = 1 , d = s.indexOf((char)max) + 1;
		
		//out(d);
		
		for (int i = v.length() - 1; i >= 0; i--) {
			ret += s.indexOf(v.charAt(i)) * k;
			k *= d;
		}
		
		return ret;
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(br.readLine());
		long ans = Long.MAX_VALUE;
		
		for (int i = 0; i < n; i++) {
			String v = br.readLine();
			ans = Math.min(ans , getDecimal(v));
		}
		
		out(ans);
	}
}