Rating changes for the last round are temporarily rolled back. They will be returned soon.
×

Package for this problem was not updated by the problem writer or Codeforces administration after we’ve upgraded the judging servers. To adjust the time limit constraint, solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then value 800 ms will be displayed and used to determine the verdict.

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

A. Dragons

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputKirito is stuck on a level of the MMORPG he is playing now. To move on in the game, he's got to defeat all *n* dragons that live on this level. Kirito and the dragons have strength, which is represented by an integer. In the duel between two opponents the duel's outcome is determined by their strength. Initially, Kirito's strength equals *s*.

If Kirito starts duelling with the *i*-th (1 ≤ *i* ≤ *n*) dragon and Kirito's strength is not greater than the dragon's strength *x*_{i}, then Kirito loses the duel and dies. But if Kirito's strength is greater than the dragon's strength, then he defeats the dragon and gets a bonus strength increase by *y*_{i}.

Kirito can fight the dragons in any order. Determine whether he can move on to the next level of the game, that is, defeat all dragons without a single loss.

Input

The first line contains two space-separated integers *s* and *n* (1 ≤ *s* ≤ 10^{4}, 1 ≤ *n* ≤ 10^{3}). Then *n* lines follow: the *i*-th line contains space-separated integers *x*_{i} and *y*_{i} (1 ≤ *x*_{i} ≤ 10^{4}, 0 ≤ *y*_{i} ≤ 10^{4}) — the *i*-th dragon's strength and the bonus for defeating it.

Output

On a single line print "YES" (without the quotes), if Kirito can move on to the next level and print "NO" (without the quotes), if he can't.

Examples

Input

2 2

1 99

100 0

Output

YES

Input

10 1

100 100

Output

NO

Note

In the first sample Kirito's strength initially equals 2. As the first dragon's strength is less than 2, Kirito can fight it and defeat it. After that he gets the bonus and his strength increases to 2 + 99 = 101. Now he can defeat the second dragon and move on to the next level.

In the second sample Kirito's strength is too small to defeat the only dragon and win.

Codeforces (c) Copyright 2010-2019 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Oct/23/2019 12:21:01 (h2).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|