import java.util.*;

public class Main {
	public static void main (String[] args)  {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long min = Long.MAX_VALUE;
		for (int i = 0; i < n; i++) {
		    char[] arr = sc.next().toCharArray();
		    int max = 0;
		    for (char c : arr) {
		        max = Math.max(max, charToInt(c));
		    }
		    max++;
		    long value = 0;
		    for (char c : arr) {
		        value *= max;
		        value += charToInt(c);
		    }
		    min = Math.min(min, value);
		}
		System.out.println(min);
	}
	
	static int charToInt(char c) {
	    if (c <= '9') {
	        return c - '0';
	    } else {
	        return c - 'A' + 10;
	    }
	}
}