#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>
#include <vector>

using namespace std;

#define REP(i,n) for(int i=0; i<n; ++i)
#define PB push_back

char ky[1010];
char t[100010];
char res[100010];

int main()
{
	while(true){
		scanf("%s", ky);
		if(ky[0] == '0') break;
		scanf("%s", t);
		for(int i=0, j=0; ; ++i, ++j){
			if(ky[i] == '\0') i = 0;
			if(t[j] == '\0'){ res[j] = '\0'; break; }
			int ile = (ky[i]-'A'+1) + t[j]-'A';
			if(ile >= 26) ile -= 26;
			res[j] = ('A' + ile);
		}
		printf("%s\n", res);
	}
	return 0;
}