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

public class Main{
    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
        ArrayList<Pair> list = new ArrayList<>(10000);
        PriorityQueue<Pair> res = new PriorityQueue<>((o1, o2) -> o1.value-o2.value);
        while(sc.hasNext()){
            int n = sc.nextInt();
            list.clear();
            res.clear();
            for (int i = 0; i < n; i++) {
                int value = sc.nextInt();
                int day = sc.nextInt();
                list.add(new Pair(day, value));
            }
            Collections.sort(list,(o1, o2) -> o1.day-o2.day);
            int days = 0;
            int le = 0, re = list.size();
            while(le<re){
                Pair p = list.get(le++);
                days = p.day;
                res.add(p);
                if (res.size() > days){
                    res.poll();
                }
            }
            int out = 0;
            while(!res.isEmpty()){
                out += res.poll().value;
            }
            writer.write(out+"\n");
        }
        writer.flush();
    }
    static class Pair{
        int day;
        int value;

        public Pair(int day, int value) {
            this.day = day;
            this.value = value;
        }
    }
}