Dragons

Dragons

Crawling in process...Crawling failedTime Limit:2000MSMemory Limit:262144KB 64bit IO Format:%I64d & %I64u

Description

Kirito is stuck on a level of the MMORPG he is playing now. To move on in the game, he's got to defeat alln dragons that live on this level. Kirito and the dragons havestrength, 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 equalss.

If Kirito starts duelling with thei-th (1 ≤ i ≤ n) dragon and Kirito's strength is not greater than the dragon's strengthx_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 byy_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 integerss and n (1 ≤ s ≤ 10⁴,1 ≤ n ≤ 10³). Thenn lines follow: the i-th line contains space-separated integers x_i and y_i (1 ≤ x_i ≤ 10⁴,0 ≤ y_i ≤ 10⁴) — thei-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.

Sample Input

Input

2 21 99100 0

Output

YES

Input

10 1100 100

Output

NO

Sample Output

YESNO

Hint

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 to2 + 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.

#include<cstdio>#include<cstring>using namespace std;const int M=1010;const int Max=999999999;struct node{    int strength,bonus;}num[M];int main(){    int s,n;    while(scanf("%d%d",&s,&n)!=EOF)    {        int i,j,a,b,min,sum=0;        bool mark[M];        memset(mark,true,sizeof(mark));        for(i=0;i<n;i++)        {            scanf("%d%d",&a,&b);            num[i].strength=a;            num[i].bonus=b;        }        for(i=0;i<n;i++)        {            min=Max;            for(j=0;j<n;j++)            {              if(mark[j]&&num[j].strength<min)              {                  min=num[j].strength;                  a=j;              }            }             mark[a]=false;            if(s>num[a].strength)            {                s+=num[a].bonus;                sum++;            }            else             break;        }        if(n==sum)         printf("YES\n");        else         printf("NO\n");    }    return 0;}