#include <stdio.h>

typedef struct {
	int key, id;
} data;

void merge_sort(data x[], int n)
{
	static data y[1001] = {};
	if (n <= 1) return;
	merge_sort(&(x[0]), n/2);
	merge_sort(&(x[n/2]), (n+1)/2);
	
	int i, p, q;
	for (i = 0, p = 0, q = n/2; i < n; i++) {
		if (p >= n/2) y[i] = x[q++];
		else if (q >= n) y[i] = x[p++];
		else y[i] = (x[p].key < x[q].key)? x[p++]: x[q++];
	}
	for (i = 0; i < n; i++) x[i] = y[i];
}

void chmin(int* a, int b)
{
	if (*a > b) *a = b;
}

int main()
{
	int i, N, w[1001], s[1001];
	data d[1001];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) {
		scanf("%d %d", &(w[i]), &(s[i]));
		d[i-1].key = w[i] + s[i];
		d[i-1].id = i;
	}
	merge_sort(d, N);
	
	const int sup = (1LL << 31) - 1;
	int j, k, dp[1001];
	for (i = 1, dp[0] = 0; i <= N; i++) dp[i] = sup;
	for (i = 0; i < N; i++) {
		for (j = i; j >= 0; j--) if (dp[j] <= s[d[i].id]) chmin(&(dp[j+1]), dp[j] + w[d[i].id]);
	}
	for (i = N; i >= 1; i--) if (dp[i] != sup) break;
	printf("%d\n", i);
	fflush(stdout);
	return 0;
}