import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class Main {

final static char[] arr = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'J', 'Q', 'K'};

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

String[] str = br.readLine().split(" ");

int len1 = str[0].length();

int len2 = str[1].length();

int max = Math.max(len1, len2);

int min = Math.min(len1, len2);

String res = "";

if (len1 < len2) {

for (int i = 0 ; i < len2 - len1; i++) {

str[0] = '0' + str[0];

}

}else {

for (int i = 0 ; i < len1 - len2; i++) {

str[1] = '0' + str[1];

}

}

char[] c1 = str[0].toCharArray();

char[] c2 = str[1].toCharArray();

for (int i = max - 1; i >= 0; i--) {

int index = max - i;

if (index % 2 == 1) {

res = arr[(c1[i] - '0' + c2[i] - '0') % 13] + res;

}

if (index % 2 == 0) {

res = arr[(((c2[i] - '0') - (c1[i] - '0')) + 10) % 10] + res;

}

}

System.out.println(res);

}

}