#include<iostream>
#include<cstdio>
#include<algorithm>
#define MAXSIZE 10000
using namespace std;
struct prod{
	int pi;
	int di;
};
bool more_p(const prod &m1,const prod &m2){
	return m1.pi>m2.pi;
}
bool less_d(const prod &m1,const prod &m2){
	return m1.di<m2.di;
}
int main(){
	struct prod P[MAXSIZE];
	int n,i,sum,t_unit;
	while(cin>>n){
		for(i=0;i<n;i++) cin>>P[i].pi>>P[i].di;
		sort(P,P+n,more_p);
		stable_sort(P,P+n,less_d);
		for(sum=P[0].pi,t_unit=1,i=1;i<n;i++){
			if(P[i].di>t_unit){
				sum+=P[i].pi;
				t_unit++;
			}
		}
		cout<<sum<<endl;
	}
	return 0;
}