#include <cstdio>
#include <algorithm>
#include <iostream>
using namespace std;
typedef pair<int,int> P;
const int MAX = 1e5+6;
int parent[MAX];
P ps[MAX];
int N;
void init()
{
	for(int i = 0;i < MAX;i++) parent[i] = i;
}
int find(int x)
{
	if(x == parent[x]) return x;
	return parent[x] = find(parent[x]);
}
void join(int x,int y)
{
	int p1 = find(x);
	int p2 = find(y);
	if(p1 == p2) return;
	if(p1 > p2) parent[p1] = p2;
	else parent[p2] = p1;
}
int main()
{
	while(cin>>N)
	{
		init();
		for(int i = 0;i < N;i++) scanf("%d%d",&ps[i].first,&ps[i].second);
		sort(ps,ps+N);
		int ans = 0;
		for(int i = N-1;i >= 0;i--)
		{
			int able = find(ps[i].second);
			if(able >= 1) {
				join(ps[i].second,able-1);
				ans += ps[i].first;
			}
			else continue;
		}
		cout<<ans<<endl;
	}
}