#include<bits/stdc++.h>
#define ll long long
#define reg register
#define db double
#define il inline
using namespace std;
const int N=1e6+5;
int n;
int head[N],to[N*2],nex[N*2];ll w[N*2],cnt=1;
void add(int u,int v,int ww){
	cnt++;
	to[cnt]=v;nex[cnt]=head[u];w[cnt]=ww;
	head[u]=cnt;
}
vector<int>huan,huan_w;
int fa[N],to_fa[N];
bool vis[N],in[N];
bool flag;
void dfs2(int x,int f){
	vis[x]=1;
	for(int i=head[x];i;i=nex[i]){
		if(!vis[to[i]])dfs2(to[i],x);
	}
}
int dao[N];
int dfs(int x,int f){
	if(dao[x]==1){
		dao[x]=2;huan.push_back(x);
		in[x]=1;
		huan_w.push_back(to_fa[x]);
		return 1;
	}
	dao[x]=1;
	for(int i=head[x];i;i=nex[i]){
		if(i==(f^1))continue;
		to_fa[to[i]]=w[i];
		if(dfs(to[i],i)){
			if(dao[x]!=2){
				huan.push_back(x);
				huan_w.push_back(to_fa[x]);
				in[x]=1;
			}else{
				return 0;
			}
			return 1;
		}
	}
}
ll d[N];
ll dp(int x,int f){
//	cout<<"dp"<<x<<endl;
	ll re=0;
	for(int i=head[x];i;i=nex[i]){
		ll y=to[i],c=w[i];
		if(y==f)continue;
		if(in[y])continue;
		re=max(re,dp(y,x));
		re=max(re,d[x]+d[y]+c);
		d[x]=max(d[x],d[y]+c); 
	}
	return re;
}
int tmp[2*N]={0};
ll summ[2*N]={0};
signed main(){
	scanf("%d",&n);
	for(int u,ww,i=1;i<=n;i++){
		scanf("%d%d",&u,&ww);
		add(u,i,ww);add(i,u,ww);
	}
	ll ans=0,maxx=0;
	for(int i=1;i<=n;i++){
		if(vis[i])continue;
		maxx=0;
		huan.clear();
		huan_w.clear();
		flag=0;
		dfs(i,0);
		dfs2(i,-1);
		for(auto j:huan){
			maxx=max(maxx,dp(j,0));
		}
		int m=huan.size();
		for(int i=1;i<=m*2;i++)summ[i]=0;
		for(int j=0;j<huan.size();j++){
			tmp[j+1]=huan[j];
			tmp[j+1+m]=huan[j];
			summ[j+2]=huan_w[j];
			summ[j+2+m]=huan_w[j];
		}
		for(int j=m+1;j<=m*2;j++){
			tmp[j]=tmp[j-m];
		}
		for(int j=1;j<=m*2;j++){
			summ[j]+=summ[j-1];
		}
		deque<int>q;
		for(int j=1;j<=m*2;j++){
			while(!q.empty()&&q.front()<=j-m)q.pop_front();
			if(j!=1){
				int x=q.front();
				maxx=max(maxx,summ[j]-summ[x]+d[tmp[x]]+d[tmp[j]]);
			}
			while(!q.empty()&&d[tmp[q.back()]]-summ[q.back()]<=d[tmp[j]]-summ[j]){
				q.pop_back();
			}
			q.push_back(j);
		}
		ans+=maxx;
	}
	cout<<ans;
	return 0;
}