import java.io.*;
import java.util.*;

public class Main {
    static ArrayList<HashMap<Integer, Integer>> dp = new ArrayList<>();
    static Block[] blocks;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        blocks = new Block[n];
        for (int i = 0; i < n; i++) {
            blocks[i] = new Block(sc.nextInt(), sc.nextInt());
            dp.add(new HashMap<>());
        }
        Arrays.sort(blocks);
        System.out.println(dfw(n - 1, 0));
    }
    
    static int dfw(int idx, int value) {
        if (idx < 0) {
            return 0;
        }
        if (!dp.get(idx).containsKey(value)) {
            int ans = dfw(idx - 1, value);
            if (blocks[idx].limit >= value) {
                ans = Math.max(ans, dfw(idx - 1, value + blocks[idx].weight) + 1);
            }
            dp.get(idx).put(value, ans);
        }
        return dp.get(idx).get(value);
    }
    
    static class Block implements Comparable<Block> {
        int weight;
        int limit;
        
        public Block(int weight, int limit) {
            this.weight = weight;
            this.limit = limit;
        }
        
        public int compareTo(Block another) {
            return another.weight + another.limit - weight - limit;
        }
        
        public String toString() {
            return weight + ":" + limit;
        }
    }
}


class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}