#include <algorithm>

#include <bitset>

#include <cctype>

#include <cerrno>

#include <clocale>

#include <cmath>

#include <complex>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <ctime>

#include <deque>

#include <exception>

#include <fstream>

#include <functional>

#include <limits>

#include <list>

#include <map>

#include <iomanip>

#include <ios>

#include <iosfwd>

#include <iostream>

#include <istream>

#include <ostream>

#include <queue>

#include <set>

#include <sstream>

#include <stdexcept>

#include <streambuf>

#include <string>

#include <utility>

#include <vector>

#include <cwchar>

#include <cwctype>

#include <stack>

#include <limits.h>

using namespace std;

#define MAXN 10010

struct info

{

        int p,d;

} a[MAXN];

int i,n,ans;

priority_queue< int,vector<int>,greater<int> > q;

inline bool cmp(info a,info b)

{

        return a.d < b.d;

}

int main()

{

        while (scanf("%d",&n) != EOF)

        {

                ans = ;

                while (!q.empty()) q.pop();

                for (i = ; i <= n; i++) scanf("%d%d",&a[i].p,&a[i].d);

                sort(a+,a+n+,cmp);

                for (i = ; i <= n; i++)

                {

                        if (q.size() < a[i].d) q.push(a[i].p);

                        else if (a[i].p > q.top())

                        {

                                q.pop();

                                q.push(a[i].p);

                        }

                }

                while (!q.empty())

                {

                        ans += q.top();

                        q.pop();

                }

                printf("%d\n",ans);

        }

        return ;

}