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

public class Main {
    static Block[] blocks;
    static ArrayList<HashMap<Integer, Integer>> dp = new ArrayList<>();
    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);
        int ans = 0;
        for (int i = n - 1; i > 0; i--) {
            ans = Math.max(ans, dfw(i - 1, blocks[i].solid) + 1);
        }
        System.out.println(ans);
    }
    
    static int dfw(int idx, int w) {
        if (w < 0) {
            return Integer.MIN_VALUE;
        }
        if (idx < 0) {
            return 0;
        }
        if (!dp.get(idx).containsKey(w)) {
            int ans = Math.max(dfw(idx - 1, w), dfw(idx - 1, Math.min(w - blocks[idx].weight, blocks[idx].solid)) + 1);
            dp.get(idx).put(w, ans);
        }
        return dp.get(idx).get(w);
    }
    
    static class Block implements Comparable<Block> {
        int weight;
        int solid;
        
        public Block(int weight, int solid) {
            this.weight = weight;
            this.solid = solid;
        }
        
        public int compareTo(Block another) {
            return (weight + solid) - (another.weight + another.solid);
        }
    }
}

class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}