import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		long ans = Long.MAX_VALUE;
				
		for(int i=0; i<n; i++) {
			String stringV = sc.next();
			Long decimalV = Long.parseLong(stringV, getMinRadix(stringV));
			ans = Math.min(decimalV, ans);
		}
		System.out.println(ans);
	}
	
	static int getMinRadix(String str) {
		int ret = 0;
		for(int i=0; i<str.length(); i++) {
			ret = Math.max(str.charAt(i), ret);
		}
		
		if(ret >= '0' && ret <= '9') {
			return ret - '0' + 1;
			
		} else if(ret >= 'A' && ret <= 'Z') {
			return ret - 'A' + 10 + 1;
		
		} else {
			throw new IllegalArgumentException("ret:"+ret);
		}	
	}
}