import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        String [] S = new String [N];
        for(int i=0; i<N; i++){
           S[i] = sc.next();
        }
        Arrays.sort(S);
        int L=S[0].length();
        int [] u = new int [L];
        int max=0;
        for(int j=0; j<L; j++){
            u[j] = S[0].charAt(j);
            if(u[j]>='0' && u[j]<='9'){
                u[j]-='0';
            }else{
                u[j]=u[j]-'A'+10;
            }
            max=Math.max(max,u[j]);
        }
        long num=0;
        for(int j=0; j<L; j++){
            num+=(long)Math.pow(max+1,L-1-j)*u[j];
        }
        System.out.println(num);
    }
}