/* -*- coding: utf-8 -*-
 *
 * 1583.cc:  No.1583 Building Blocks - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 1000;
const long long LINF = 1LL << 62;

/* typedef */

typedef long long ll;
typedef pair<int,int> pii;

/* global variables */

pii ps[MAX_N];
ll dp[MAX_N + 1];

/* subroutines */

inline void setmin(ll &a, ll b) { if (a > b) a = b; }

/* main */

int main() {
  int n;
  scanf("%d", &n);

  for (int i = 0; i < n; i++) {
    int w, s;
    scanf("%d%d", &w, &s);
    ps[i] = pii(w + s, w);
  }
  sort(ps, ps + n);

  fill(dp, dp + n + 1, LINF);
  dp[0] = 0;

  for (int i = 0; i < n; i++) {
    int wi = ps[i].second, si = ps[i].first - wi;
    for (int j = i; j >= 0; j--)
      if (dp[j] <= si)
	setmin(dp[j + 1], dp[j] + wi);
  }

  int maxj = 0;
  for (int j = n; j >= 0; j--)
    if (dp[j] < LINF) { maxj = j; break; }

  printf("%d\n", maxj);
  return 0;
}