PAT1048

#include<iostream>
#include <iomanip>
#include <cstdio>
#include<string>
#include<vector>
#include<array>
#include<math.h>
#include <ctype.h>
#include<algorithm>
using namespace std;
int main()
{
	string a, b,c;
	cin >> a >> b;
	int i,temp;
	reverse(a.begin(), a.end());
	reverse(b.begin(), b.end());
	int l1 = a.length();
	int l2 = b.length();
	char str[14] = { "0123456789JQK" };
	if (l1 > l2)
		b.append(l1 - l2, '0');
	else
		a.append(l2 - l1, '0');
	for (i = 0; i < a.length(); i++) 
	{
		if (i % 2 == 0) 
		{
			c += str[(a[i] - '0' + b[i] - '0') % 13];
		}
		else 
		{
			temp = b[i] - a[i];
			if (temp < 0) 
				temp = temp + 10;
			c += str[temp];
		}
	}
	reverse(c.begin(), c.end());
	cout << c;
	return 0;
}