#include <iostream>
using namespace std;
int main() {
	string k,c;
	cin>>k>>c;
	for (int i=0;i<c.length();i++) {
		int t=(k[i%k.length()]&31)-1;
		c[i]=(c[i]&31)-t>0?c[i]-t:c[i]-t+26;
	}
	cout<<c<<endl;
	return 0;
}