# include <iostream>
# include <cstdio>
# include <cstring>
# include <queue>
# include <algorithm>
using namespace std;
const int maxn=1000100;
priority_queue <int> q;
struct homework{
    int time,score;
}hw[maxn];
int n;
int hwcomp(const homework &a,const homework &b)
{
    return a.time>b.time;
}

inline void read(int &x)
{
    char ch=getchar();
    while(ch<'0'||ch>'9') ch=getchar();
    x=0;
    while(ch>='0'&&ch<='9')
    {
        x*=10;x+=ch-'0';
        ch=getchar();
    }
    
}

int main()
{int maxt,k=0,ans=0,time,score;
  //  freopen("credits.in","r",stdin);
  //  freopen("credits.out","w",stdout);
    scanf("%d",&n);
    for(int i=0;i<n;++i)
    { read(time);hw[i].time=time;
      read(score);hw[i].score=score;
    }
    sort(hw+0,hw+n,hwcomp);
    maxt=hw[0].time;
    for(int i=maxt;i>=1;--i)
    {
        while(hw[k].time==i&&k<n)
          q.push(hw[k++].score);
        if(!q.empty())
        {ans+=q.top();
         q.pop();
        }
    }
    printf("%d\n",ans);
}