#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;

int n;
vector<pair<int,int> > t;
int f[2][6000];

int main() {
	int w,s;
	while (scanf("%d %d",&w,&s)==2) {
		t.push_back({s,w});
	}
	n=t.size();
	sort(t.begin(),t.end());
	int inf=1e9;
	f[0][0]=0;
	for (int k=1;k<=n;k++) f[0][k]=inf;
	for (int i=1;i<=n;i++) {
		s=t[i-1].first; w=t[i-1].second;
		f[i%2][0]=0;
		for (int k=1;k<=n;k++) f[i%2][k]=inf;
		for (int k=1;k<=i;k++) {
			f[i%2][k]=f[(i-1)%2][k];
			if (s>=f[(i-1)%2][k-1]+w) {
				f[i%2][k]=min(f[i%2][k], f[(i-1)%2][k-1]+w);
			}
		}
	}
	int r=0;
	while (r<n && f[n%2][r+1]!=inf) r++;
	printf("%d\n",r);
	return 0;
}