#include <bits/stdc++.h>
using namespace std;
const int N=1010;
int n,x,ver[2*N],nxt[2*N],hd[N],idx,ans,vis[N],f[2*N],s[N],su,l;
struct node{
	int w,idx;
}a[N];
void add(int y,int z){
	ver[++idx]=z;
	nxt[idx]=hd[y];
	hd[y]=idx;
}
void dfs(int p,int fa){
	if(!s[p]) su++,s[p]=1;
	for(int i=hd[p];i;i=nxt[i]){
		if(ver[i]!=fa&&!vis[ver[i]]&&!f[i]){
			vis[ver[i]]=1;
			dfs(ver[i],p);
			vis[ver[i]]=0;
		}
	}
}
void fx(int i,int sum){
	if(i>=n){
		memset(s,1,sizeof(s));
		int cnt=n*(n-1)/2;
		for(int j=1;j<=n;j++){
			if(!s[j]) memset(vis,0,sizeof(vis)),su=0,dfs(j,0),cnt=cnt-(su*max(su-1,0)/2);
		}
		ans=max(ans,cnt-sum);
		return;
	}
	else{
		f[a[i].idx]=f[a[i].idx+1]=1;
		fx(i+1,sum+a[i].w);
		f[a[i].idx]=f[a[i].idx+1]=0;
		fx(i+1,sum);
	}                  
}
int main(){
	freopen("delete.in","r",stdin);
	freopen("delete.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<n;i++){
		scanf("%d%d",&l,&a[i].w);
		a[i].idx=idx+1;
		add(l,i+1),add(i+1,l);
	}
	fx(1,0);
	printf("%d",ans);
	return 0;
}