import java.io.*;
import java.nio.*;
import java.nio.file.*;
import java.util.*;
import java.util.concurrent.*;
import java.math.*;
import java.util.stream.*;

public class Main {
	public static void main(String... args) throws Throwable {
		Scanner in = new Scanner(System.in);
		
		ArrayList<Long> list = new ArrayList<>();
		
		int cnt = in.nextInt();
		for (int i = 0; i < cnt; i++) {
			String str = in.next();
			list.add(Long.parseLong(str, str.codePoints().map(c -> (int)'A' <= c ? (10 + (c - (int)'A') + 1) : (c - (int)'0' + 1)).max().getAsInt()));
		}
		System.out.println(Collections.min(list));
	}
}