#include<bits/stdc++.h>
using namespace std;
int main(){
string a, b;
cin >> a >> b;
int x = 0;
int i = a.size() - 1, j = b.size() - 1;
string s = "";
while(i >= 0 || j >= 0 || x > 0){
int n1 = (i >= 0) ? a[i] - 'A' : 0;
int n2 = (j >= 0) ? b[j] - 'A' : 0;
int sum = n1 + n2 + x;
x = sum / 20;
int r = sum % 20;
s = char(r + 'A') + s;
i--,j--;
}
while(s[0] == 'A') s.erase(0, 1);
cout << s;
return 0;
}