题目描述
Problem Description
ZngivaeL is taking his high school entrance exam. He has 4 subjects to be graded (with ratings $\texttt{ABCD}$).
ZngivaeL has three options for his high school: key high school, regular high school, and vocational high school. The admission difficulty of these three high schools decreases in the order of key high school, regular high school, and vocational high school.
If ZngivaeL scores all subjects with a rating of $\texttt{C}$ or higher (i.e., $\texttt{A, B, C}$), he can choose to attend regular high school, otherwise, he can only choose to attend vocational high school.
Furthermore, to be admitted to key high school, ZngivaeL must have ratings of $\texttt{A}$ or $\texttt{B}$ in all subjects, and at least one subject must be rated $\texttt{A}$.
Given the ratings for each subject for ZngivaeL, determine the highest difficulty high school he can attend.
Input Format
Input consists of one line containing four uppercase letters between $\texttt{A}$ and $\texttt{D}$, representing ZngivaeL's ratings for each subject.
Output Format
Output a single string indicating the answer for each set of data.
If ZngivaeL can attend key high school, output I'm so happy.; if he can attend regular high school but not key high school, output This is ok.; if he can only attend vocational high school, output Never give up..
Sample Input and Output
Sample Input #1
ABCD
Sample Output #1
Never give up.
Sample Input #2
BBBB
Sample Output #2
This is ok.
Sample Input #3
AAAA
Sample Output #3
I'm so happy.
Sample Input #4
CCCA
Sample Output #4
This is ok.
Notes
Sample Explanation
Sample Explanation #1: Since there is a subject rated $\texttt{D}$, he can only attend vocational high school.
Sample Explanation #2: All subjects are rated $\texttt{B}$. Since there is no subject rated $\texttt{A}$, he can attend regular high school but not key high school.
Data Size and Constraints
It is guaranteed that the four input characters are all uppercase letters among $\texttt{A, B, C, D}$.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分