#include <bits/stdc++.h>
using namespace std;
int main(){
	string s;
	cin>>s;
	int q;
	cin>>q;
	while(q--){
		int l,r;
		bool flag=false;
		cin>>l>>r;
		l--;
		r--;
		string t=s.substr(l,r+1);/**/
		for(int i=t.length()-1;i>=0;i--){
			if(t[i]!='a'){
				t[i]--;
				flag=true;
				break;
			}
			t[i]='z';
		}
		if(!flag){
			cout<<"NULL\nHappy Chinese New Year!\n";
			break;
		}
		bool flagg=false;
		for(int i=0;i<s.length()-t.length();i++){/**/
			for(int j=0;j<t.length();j++){
				if(s[i+j]!=t[i+j]){
					break;
					flagg=true;
				}
			}
			if(!flagg){
				cout<<t<<endl;
				cout<<"Happy New Year!\n";
				break;
			}
		}
		if(flagg){
			cout<<t<<endl;
			cout<<"Happy Chinese New Year!\n";
		}
	}
    return 0;
}

我的输出：

bcc
Happy New Year!
ccaacbzy
Happy New Year!
a
Happy New Year!
zy
Happy New Year!
aacbzy
Happy New Year!

正确输出：

bcc
Happy New Year!
cbzz
Happy New Year!
a
Happy New Year!
zy
Happy Chinese New Year!
NULL
Happy Chinese New Year!