# Problem D

Speedrun

You aspire to become a top Minecraft survival speedrunner.
So, you need to come up with a strategy to do every necessary
task quickly and efficiently. After watching a lot of previous
world record speedruns, you noticed that the first day is the
most crucial.

You need to finish at least $G$ tasks on the first Minecraft day
for the speedrun to succeed. Each Minecraft day is $24\, 000$ ticks long, and thus to be
a true gamer, you decided to do your math in Minecraft lingo.
You can only work on one task at a time, and you cannot start
another task before finishing your current task. Each task can
only be done in a specific period of time $0 \leq t_{start} < t_{end} \leq 24\,
000$. Note: so long as the starting time of a task is
greater than or equal to the end time of the previous task, the
task can be scheduled with no conflict.

Given $G$, the minimum
number of tasks you need to do on the first Minecraft day;
$N$, the number of
possible tasks you can do, and their corresponding time period,
determine whether this run can be successful.

## Input

The first line consists of $2$ space-separated integers,
$0 < G \leq N <
10^5$, the number of tasks you need to do on the first
day and the total number of tasks. The next $N$ lines each consist of $2$ integers $t_{start}$ and $t_{end}$, where $0 \leq t_{start} < t_{end} \leq 24\,
000$.

## Output

Output “`YES`” if the run can be
potentially successful, and “`NO`”
otherwise.

Sample Input 1 | Sample Output 1 |
---|---|

2 3 0 20 20 24000 19 21 |
YES |

Sample Input 2 | Sample Output 2 |
---|---|

2 4 3 5 1 4 4 24000 0 17000 |
YES |

Sample Input 3 | Sample Output 3 |
---|---|

3 4 1 501 500 1001 1000 1501 1500 2000 |
NO |