import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
	
		String[] inputs = new String[N];
		for(int i = 0; i < N; i++){
			inputs[i] = sc.next();
		}
		
		long min = Long.MAX_VALUE;
		for(String str : inputs){
			char latest = '\0';
			for(char c : str.toCharArray()){
				if(latest < c){
					latest = c;
				}
			}
			
			final int radix = ('0' <= latest && latest <= '9') ? (Character.getNumericValue(latest) + 1) : (10 + (latest - 'A' + 1));
			
			min = Math.min(min, Long.parseUnsignedLong(str, radix));
		}
		
		System.out.println(min);
		
	}
	
}