#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

struct Candy {
  int v;
  int t;

  Candy(int v = -1, int t = -1) {
    this->v = v;
    this->t = t;
  }

  bool operator<(const Candy &n) const {
    return v + t < (n.v + n.t);
  }
};

int main() {
  int N;
  cin >> N;
  for (int i = 0; i < N; ++i) {
  }

  vector<Candy> candy_list;
  for (int i = 0; i < N; ++i) {
    int v, t;
    cin >> v >> t;

    candy_list.push_back(Candy(v, t));
  }

  sort(candy_list.begin(), candy_list.end());
  int dp[10010];
  memset(dp, -1, sizeof(dp));
  dp[0] = 0;
  int ans = 0;

  for (int i = 0; i < candy_list.size(); ++i) {
    Candy candy = candy_list[i];

    for (int v = 10000; v >= 0; --v) {
      if (dp[v] == -1) continue;

      int nv = v + candy.v;
      int cnt = candy.v;
      if (v >= candy.t) cnt = 1;
      nv = min(nv, 10000);

      dp[nv] = max(dp[nv], dp[v] + cnt);
      ans = max(ans, dp[nv]);
    }
  }

  cout << ans << endl;

  return 0;
}