希望考试能遇到这种题

#include<bits/stdc++.h>
using namespace std;
string b,c;
int main(){
    cin>>b>>c;
    for(int i=0;i<c.length();++i){
        char a=(char)((c[i]-(b[i%b.length()]|32)+'a'));
        while((c[i]<='Z'&&c[i]>='A')&&a<'A')a+=26;
        while((c[i]<='Z'&&c[i]>='A')&&a>'Z')a-=26;
        while((c[i]<='z'&&c[i]>='a')&&a<'a')a+=26;
        while((c[i]<='z'&&c[i]>='a')&&a>'z')a-=26;
        if((c[i]<='Z'&&c[i]>='A')&&a<='z'&&a>='a')a-=32;
        if((c[i]<='z'&&c[i]>='a')&&a<='Z'&&a>='A')a+=32;
        cout<<a;
    }
    return 0;
}