1016

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
    // write your code here
        Scanner sc=new Scanner(System.in);
        int A=sc.nextInt();
        int DA=sc.nextInt();
        int B=sc.nextInt();
        int DB=sc.nextInt();
        char[] a=(A+"").toCharArray();
        char[] b=(B+"").toCharArray();
        int x=0;
        int y=0;
        double PA=0;
        double PB=0;
        for (int i=0;i<a.length;i++){
            if ((Integer.parseInt(a[i]+""))==DA){
                x++;
            }
        }
        for (int i=0;i<b.length;i++){
            if ((Integer.parseInt(b[i]+""))==DB){
                y++;
            }
        }
        for (double i=Math.pow(10,x-1);i>=1;i=i/10){
            PA=PA+DA*i;
        }
        for (double i=Math.pow(10,y-1);i>=1;i=i/10){
            PB=PB+DB*i;
        }
        System.out.println((int)(PA+PB));
    }
}