#include <iostream>
//#include <stdio.h>
#include <string>

using namespace std;




int main(){
int a,b,c;
string s,n;

while(true){

getline(cin,s);
if(s[0]=='0' && s.size()==1) break;
getline(cin,n);

b=n.size();
//cout<<s<<endl;
while(s.size()<b){
 s=s+s;
}
//cout<<s<<endl;
a=0;
while(a<b){
	c=int(n[a])+int(s[a])-2*int('A')+1;
	c=c%26;
	cout<<char(int('A')+c);
	a++;

}
cout<<endl;


}
return 0;
}