#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,ans;
struct work{
	int tim,v;
}w[100100];
int t=0;
bool cmp(work x,work y){
	if(x.tim==y.tim)return x.v>y.v;
	return x.tim<y.tim;
}
signed main(){
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>w[i].tim>>w[i].v;
	}
	sort(w,w+n,cmp);
	for(int i=0;i<n;i++){
		if(w[i].tim<t)continue;
		t=w[i].tim+1;
		ans+=w[i].v;
	}
	cout<<ans;
	return 0;
}

如果大佬不想改也可以给Hack数据