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

public class Main {
    static House[] houses;
    static int[][] dp;
    static int[] maxes;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        houses = new House[n];
        for (int i = 0; i < n; i++) {
            String[] line = br.readLine().split(" ", 2);
            houses[i] = new House(Integer.parseInt(line[0]), Integer.parseInt(line[1]));
        }
        Arrays.sort(houses);
        maxes = new int[n];
        maxes[0] = houses[0].limit;
        for (int i = 1; i < n; i++) {
            maxes[i] = Math.max(maxes[i - 1], houses[i].limit);
        }
        dp = new int[n][10001];
        for (int[] arr : dp) {
            Arrays.fill(arr, -1);
        }
        System.out.println(dfw(n - 1, 0));
    }
    
    static int dfw(int idx, int value) {
        if (idx < 0) {
            return 0;
        }
        if (value > maxes[idx]) {
            return 0;
        }
        if (dp[idx][value] < 0) {
            dp[idx][value] = dfw(idx - 1, value);
            if (houses[idx].limit > value) {
                dp[idx][value] = Math.max(dp[idx][value], dfw(idx - 1, value + houses[idx].gain) + houses[idx].gain);
            }
        }
        return dp[idx][value];
    }
    
    static class House implements Comparable<House> {
        int gain;
        int limit;
        int key;
        
        public House(int gain, int limit) {
            this.gain = gain;
            this.limit = limit;
            key = gain + limit;
        }
        
        public int compareTo(House another) {
            return another.key - key;
        }
    }
}