题目描述
Problem Description
Given a positive integer $ N $ and an operator $\mathrm{op}$ (<, =, >), determine whether there exists a set $ X $ that satisfies all the following conditions, and if so, construct one such set.
- Each element of $ X $ is a non-negative integer between $ 0 $ and $ 10^9 $ inclusive.
- $ |X| = N $. (Here, $ |X| $ denotes the number of elements in the set $ X $)
- Let $S = \{ a + b \mid a, b \in X \}, D = \{ a - b \mid a, b \in X \}$. Then $|S| \mathrm{op} |D|$ holds.
- In other words, $ S $ and $ D $ are the sets of possible sums and differences of elements in $ X $, respectively. Note that the case $ a = b $ is included in the definition. (Refer to the examples below)
For example, when $X = \{2, 0, 1, 9\}$, $S = \{0, 1, 2, 3, 4, 9, 10, 11, 18\}$ and $D = \{-9, -8, -7, -2, -1, 0, 1, 2, 7, 8, 9\}$, so $ |S| < |D| $.
Input Format
$ N $ $\mathrm{op}$
Output Format
If a set satisfying the conditions exists, output one such set. The set should be output with its elements separated by spaces.
If no such set exists, output Merry Christmas! instead.
Sample Input and Output
Sample Input #1
4 <
Sample Output #1
2 0 1 9
Sample Input #2
4 >
Sample Output #2
Merry Christmas!
Notes/Hints
Constraints
- $1 \leq N \leq 2,019$.
- $\mathrm{op}$ is one of
<,=,>.
Sample Explanation 1
This is the example given in the problem statement.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
4 <
样例输出
2 0 1 9