#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
int n;
struct hehe
{
	int a,b;
}w[100001];
unsigned long long answer=0;
int q[100001][2],tou=1,wei=1,ji=0;
int cmp(const void *a,const void *b);
int main()
{
	freopen ("joba.in","r",stdin);
	freopen ("joba.out","w",stdout);
	cin>>n;
	for (int i=0;i<n;i++)
	{
		cin>>w[i].a>>w[i].b;
	}
	qsort(w,n,sizeof(w[0]),cmp);
	for (int i=0;i<n;i++)
	{
		if (ji<w[i].a)
		{
			ji++;
			q[wei][0]=w[i].a;
			q[wei][1]=w[i].b;
			wei++;
		}
		else
		{
			if (q[tou][1]<w[i].b)
			{
				tou++;
				q[wei][0]=w[i].a;
				q[wei][1]=w[i].b;
				wei++;
			}
		}
	}
	for (int i=tou;i<wei;i++)
		answer+=q[i][1];
	cout<<answer;
	return 0;
}
int cmp(const void *e,const void *f)
{
	struct hehe *c=(struct hehe *)e;
	struct hehe *d=(struct hehe *)f;
	if (c->a==d->a)
		return (c->b > d->b) ?1:-1;
	else
		return (c->a > d->a) ?1:-1;
}