#include <cstdio>

 #include <cstring>

 #define LL long long

 const LL Maxn=;

 struct Edge{LL to,next;}edge[Maxn<<];

 LL head[Maxn],F[Maxn],G[Maxn],cnt,U,V,E,vis[Maxn],a[Maxn],n,Ans;

 inline void Add(LL u,LL v) {edge[++cnt].to=v;edge[cnt].next=head[u];head[u]=cnt;}

 inline LL Max(LL x,LL y) {return x>y?x:y;}

 void Dfs(LL u,LL fa)

 {

     vis[u]=true;

     for (LL i=head[u];i!=-;i=edge[i].next)

     {

         if (edge[i].to==fa) continue;

         if (vis[edge[i].to])

         {

             U=u,V=edge[i].to;

             E=i;

             continue;

         }

         Dfs(edge[i].to,u);

     }

 }

 void Dp(LL u,LL fa,LL Ban)

 {

     F[u]=a[u],G[u]=;

     for (LL i=head[u];i!=-;i=edge[i].next)

     {

         if (i==Ban || (i^)==Ban || edge[i].to==fa) continue;

         Dp(edge[i].to,u,Ban);

         F[u]+=G[edge[i].to];

         G[u]+=Max(F[edge[i].to],G[edge[i].to]);

     }

 }

 int main()

 {

     scanf("%lld",&n);

     memset(head,-,sizeof(head)); cnt=;

     for (LL i=;i<=n;i++)

     {

         LL u;

         scanf("%lld%lld",&a[i],&u);

         Add(u,i),Add(i,u);

     }

     for (LL i=;i<=n;i++)

         if (!vis[i])

         {

             Dfs(i,);

             Dp(U,,E);

             LL Ret=G[U];

             Dp(V,,E);

             Ret=Max(Ret,G[V]);

             Ans+=Ret;

         }

     printf("%lld\n",Ans);

     return ;

 }