题号：NC15803
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 32 M，其他语言64 M
64bit IO Format: %lld
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 32 M，其他语言64 M
64bit IO Format: %lld
题目描述
It’s universally acknowledged that there’re innumerable trees in the campus of HUST.
One day the tree manager of HUST asked you to sort N trees increasing by their heights ai. Because you were a warm-hearted and professional programmer, you immediately wrote the Bubble Sort to finish the task. However, you were so tired that made a huge mistake:
for(int i=1;i<n;i++)
for(int j=1;j<=n-i;j++)
if(a[j+k]<a[j])swap(a[j+k],a[j]);
Usually k=1 is the normal Bubble Sort. But you didn't type it correctly. When you now realize it, the trees have been replanted. In order to fix them you must find the first place that goes wrong, compared with the correctly sorted tree sequence.
If every trees are in their correct places then print -1. And you should know k can be equal to 1 which means you didn't make any mistake at all. Also you don't need to consider the part j+k beyond n.
输入描述:
The first line contains two integers Nand K
as described above.
Then the next line are N integers indicating the unsorted trees.
输出描述:
A integer in a single line, indicating the first place that goes wrong. Or -1 means no mistake.