#include<bits/stdc++.h>
using namespace std;
char s[1009],k[109],c[1009];
char mm(char s1,char k1){
	s1-=k1-'a';
	if(s1<'a')
		s1+=26;
	return s1;//单个字符转换
}
int main(){
	cin>>k;
	cin>>s;
	char k2[109],s2[1009];
	strcpy(k2,k);
	strcpy(s2,s);
	for(int i=0;i<strlen(s2);i++)
	{
		if('A'<=s2[i]&&s2[i]<='Z')
			s2[i]+=32;
	}
	for(int i=0;i<strlen(k2);i++)
	{
		if('A'<=k2[i]&&k2[i]<='Z')
			k2[i]+=32;
	}//统一大小写
	int len=strlen(k2);
	for(int i=0;i<=strlen(s2);i++)
	{
		c[i]=mm(s2[i],(k2[i%(len)]));
		if(s[i]<='Z')//大小写转换
			c[i]-=32;
	}
	cout<<c;
	return 0;
}

求dalao解释