#pragma GCC optimize ("O2")
#pragma GCC target ("avx")
#include<bits/stdc++.h>
#include<iostream>
#include<cstring>
//#include<atcoder/all>
//using namespace atcoder;


using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

int dp[1001][1001];
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	int N;
	cin >> N;

	pair<int, int> WS[1000];
	rep(i, N) {
		int w, s;
		cin >> w >> s;
		WS[i] = { s+w,w };
	}
	sort(WS, WS + N);
	reverse(WS, WS + N);

	rep(i, N + 1) rep(j, N + 1) dp[i][j] = -1;
	dp[0][0] = 2.1e9;
	rep(i, N) {
		rep(j, N) {
			chmax(dp[i + 1][j], dp[i][j]);
			if (dp[i][j] >= 0) chmax(dp[i + 1][j + 1], min(dp[i][j] - WS[i].second, WS[i].first - WS[i].second));
		}
	}
	int kotae = 0;
	rep1(j, N) if (dp[N][j] >= 0) kotae = j;

	co(kotae);

	Would you please return 0;
}