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最新推荐文章于 2021-03-17 20:14:57 发布

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博客讲述了在Pindows XR操作系统中，如何在文件夹按行排列的情况下，最少框选多少次来选择并删除从a到b的文件夹。给出了三种可能的情况：一次、两次或三次，并提供了AC代码来解决这个问题。

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2188: Frames

Time Limit: 2 Sec Memory Limit: 256 MB
Submit: 64 Solved: 26
[Submit][Status][Web Board]

Description

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Throughout Igor K.'s life he has had many situations worthy of attention. We remember the story with the virus, the story of his mathematical career and of course, his famous programming achievements. However, one does not always adopt new hobbies, one can quit something as well.

This time Igor K. got disappointed in one of his hobbies: editing and voicing videos. Moreover, he got disappointed in it so much, that he decided to destroy his secret archive for good.

Igor K. use Pindows XR operation system which represents files and folders by small icons. At that, m icons can fit in a horizontal row in any window.

Igor K.'s computer contains n folders in the D: disk's root catalog. The folders are numbered from 1 to n in the order from the left to the right and from top to bottom (see the images). At that the folders with secret videos have numbers from a to binclusive. Igor K. wants to delete them forever, at that making as few frame selections as possible, and then pressing Shift+Delete exactly once. What is the minimum number of times Igor K. will have to select the folder in order to select folders from a to b and only them? Let us note that if some selected folder is selected repeatedly, then it is deselected. Each selection possesses the shape of some rectangle with sides parallel to the screen's borders.

Input

The only line contains four integers n, m, a, b (1≤n,m≤109, 1≤a≤b≤n). They are the number of folders in Igor K.'s computer, the width of a window and the numbers of the first and the last folders that need to be deleted.

Output

Print a single number: the least possible number of times Igor K. will have to select the folders using frames to select only the folders with numbers from a to b.

Examples

Input

11 4 3 9

Output

Input

20 5 2 20

Output

Note

The images below illustrate statement tests.

The first test:

In this test we can select folders 3 and 4 with out first selection, folders 5, 6, 7, 8 with our second selection and folder 9 with our third, last selection.

The second test:

In this test we can first select all folders in the first row (2, 3, 4, 5), then − all other ones.

题目大意：n个文件夹，按每行m个排列，从a号到b号最少要框几次，才能全部选中。

思路：很明显不管数目再多，都只有三种可能性，框一次，框两次和框三次。所以只要分析出前两种的判断条件其余就都是框三次了。

框一次：起点终点在同一行，起点在头并且终点在尾，m为1.

框二次：起点在头或终点在尾，起点终点行数差1。

else

框三次。

AC代码：

#include<iostream>
#include<queue>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int main()
{
 int n,m,l,r;
 while(~scanf("%d %d %d %d",&n,&m,&l,&r))
 {
     int a=l/m;//起点所在的行数
     if(l%m!=0)
     a++;
     int b=r/m;//终点所在的行数
     if(r%m!=0)
        b++;

     if(a==b||m==1||l%m==1&&r%m==0)//
     {
         cout<<1<<endl;
     }
     else if(l%m==1||r%m==0||(b-a)==1||l%m-1==r%m)
        cout<<2<<endl;
     else
        cout<<3<<endl;
 }

    return 0;
}