题解

#include<bits/stdc++.h>
using namespace std;
int main(){
	string s;
	cin>>s;
	for(int i=s.size()-1;i>=0;i--){
		s[i]+=3,s[i]-=((s[i]>'z'||(s[i]>'Z'&&s[i]<'a'))?26:0);
		s[i]=((s[i]>='A'&&s[i]<='Z')?s[i]+32:s[i]-32);
		cout<<s[i];
	}
	putchar('\n');
    return 0;
}