#include<iostream>

#include<algorithm>

#include<vector>

using namespace std;

#define LL long long

const int N = 5e5+;

int n;

struct Task {

    LL t,v;

    bool operator<(const Task &a) {

        return v == a.v? t>a.t: v>a.v;

    }

};

vector<Task> task;

int vis[N];

int main()

{

    ios::sync_with_stdio(false);

    while(cin>>n)

    {

        LL ans=, count=;

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

            vis[i]=;

            LL t,v;

            cin>>t>>v;

            task.push_back(Task{t,v});

        }

        sort(task.begin(), task.end());

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

            int t = task[i].t;

            while(vis[t] && t) t--;

            if(!t) continue;

            vis[t] = ;

            ans += task[i].v;

            if(++count == n)

                break;

        }

        cout<<ans<<endl;

        task.clear();

    }

    return ;

}