import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {

	public static void main(String[] args) {
		new Main().run();
	}
	
	long pow(long a,long n) {
		long ret=1;
		for(;n>0;n/=2,a*=a)if(n%2==1)ret*=a;
		return ret;
	}
	
	long g(char c) {
		if((int)(c-'0')>=0&&(int)(c-'0')<=9)return (int)(c-'0');
		else return (int)(c-'A'+10);

	}
	
	long f(char[] cs,long base) {
		long ret=0;
		for(int i=0;i<cs.length;++i) {
			ret+=g(cs[i])*pow(base,cs.length-1-i);
		}
		return ret;
	}

	void run() {
		Scanner sc = new Scanner(System.in);
		long n=sc.nextInt();
		long ans=Long.MAX_VALUE;
		for(int i=0;i<n;++i) {
			char[] cs=sc.next().toCharArray();
			long base=0;
			for(char c:cs) {
				base=Math.max(base, g(c)+1);
			}
			ans=Math.min(ans, f(cs,base));
		}
		System.out.println(ans);
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}