#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<set>
#include<map>
#include<stack>
#include<complex>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<deque>
#include<cstring>

using namespace std;
// using namespace __gnu_cxx;

typedef long long ll;
typedef double db;
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int,int> pii;

#define INF (1<<30)
#define PB push_back
#define FI first
#define SE second
#define REP(i,n) for(int (i)=0;(i)<(n);++(i))
#define FUP(i,a,b) for(int (i)=(a);(i)<=(b);++(i))
#define FDN(i,a,b) for(int (i)=(a);(i)>=(b);--(i))

char t1[200000];
char t2[200000];

int main(){
    while(true){
        scanf("%s", t1);
        if(t1[0] == '0') break;
        scanf("%s", t2);
        int n = strlen(t1);
        int m = strlen(t2);
        int w = 0;
        REP(i,m){
            char cc = t2[i] - 'A';
            cc += t1[w] - 'A' + 1;
            if(cc >= 26) cc -= 26;
            putchar('A' + cc);
            w++;
            if(w >= n) w = 0;
        }
        putchar('\n');
    }
    return 0;
}