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Humanity's Last Code Exam / 2017_H / Scenery

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atcoder

question content

### Problem Statement You have decided to spend a day of your trip to Rapid City taking photographs of the South Dakota Badlands, which are renowned for their spectacular and unusual land formations. You are an amateur photographer, yet very particular about lighting conditions. After some careful research, you have located a beautiful location in the Badlands, surrounded by picturesque landscapes. You have determined a variety of features that you wish to photograph from this location. For each feature, you have identified the earliest and latest time of day at which the position of the sun is ideal. However, it will take quite a bit of time to take each photograph, given the need to reposition the tripod and camera and your general perfectionism. So you are wondering if it will be possible to successfully take photographs of all these features in one day. ### Input The first line of the input contains two integers

n

(1 ≤

n

≤ 10\(^4\)) and

t

(1 ≤

t

≤ 10\(^5\)), where

n

is the number of desired photographs and

t

is the time you spend to take each photograph. Following that are

n

additional lines, each describing the available time period for one of the photographs. Each such line contains two nonnegative integers

a

and

b

, where

a

is the earliest time that you may begin working on that photograph, and

b

is the time by which the photograph must be completed, with \( a + t ≤ b ≤ 10^9 \). ### Output Display `yes` if it is possible to take all

n

photographs, and `no` otherwise. ### Sample Input 1

Plain-text mathematical notation (without MathML)

### Problem Statement

You have decided to spend a day of your trip to Rapid City taking photographs of the South Dakota Badlands, which are renowned for their spectacular and unusual land formations. You are an amateur photographer, yet very particular about lighting conditions.

After some careful research, you have located a beautiful location in the Badlands, surrounded by picturesque landscapes. You have determined a variety of features that you wish to photograph from this location. For each feature, you have identified the earliest and latest time of day at which the position of the sun is ideal. However, it will take quite a bit of time to take each photograph, given the need to reposition the tripod and camera and your general perfectionism. So you are wondering if it will be possible to successfully take photographs of all these features in one day.

### Input

The first line of the input contains two integers n (1 ≤ n ≤ 10\(^4\)) and t (1 ≤ t ≤ 10\(^5\)), where n is the number of desired photographs and t is the time you spend to take each photograph. Following that are n additional lines, each describing the available time period for one of the photographs. Each such line contains two nonnegative integers a and b, where a is the earliest time that you may begin working on that photograph, and b is the time by which the photograph must be completed, with \( a + t ≤ b ≤ 10^9 \).

### Output

Display `yes` if it is possible to take all n photographs, and `no` otherwise.

### Sample Input 1

Original LaTeX notation

### Problem Statement

You have decided to spend a day of your trip to Rapid City taking photographs of the South Dakota Badlands, which are renowned for their spectacular and unusual land formations. You are an amateur photographer, yet very particular about lighting conditions.

After some careful research, you have located a beautiful location in the Badlands, surrounded by picturesque landscapes. You have determined a variety of features that you wish to photograph from this location. For each feature, you have identified the earliest and latest time of day at which the position of the sun is ideal. However, it will take quite a bit of time to take each photograph, given the need to reposition the tripod and camera and your general perfectionism. So you are wondering if it will be possible to successfully take photographs of all these features in one day.

### Input

The first line of the input contains two integers \( n \) (1 ≤ \( n \) ≤ 10\(^4\)) and \( t \) (1 ≤ \( t \) ≤ 10\(^5\)), where \( n \) is the number of desired photographs and \( t \) is the time you spend to take each photograph. Following that are \( n \) additional lines, each describing the available time period for one of the photographs. Each such line contains two nonnegative integers \( a \) and \( b \), where \( a \) is the earliest time that you may begin working on that photograph, and \( b \) is the time by which the photograph must be completed, with \( a + t ≤ b ≤ 10^9 \).

### Output

Display `yes` if it is possible to take all \( n \) photographs, and `no` otherwise.

### Sample Input 1

Code

2 10
0 15
5 20


### Sample Output 1

Code

yes


### Sample Input 2

Code

2 10
1 15
0 20


### Sample Output 2

Code

no


### Sample Input 3

Code

2 10
5 30
10 20


### Sample Output 3

Code

yes

question title

Scenery

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Source and history

upstream_id / Original problem ID: 2017_H
task_id: 4a4e3687-9c3a-505d-b8eb-9446c24cf1c1
task_key: ICPC~2dWorld~2dFinals--examples--2017~5fH
task_revision_id: 1
config / split: ICPC-World-Finals / examples

Official source

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