One Big Software Company has n employees numbered from 1 to n. The director is assigned number 1. Every employee of the company except the director has exactly one immediate superior. The director, of course, doesn't have a superior.

We will call person a a subordinates of another person b, if either b is an immediate supervisor of a, or the immediate supervisor of a is a subordinate to person b. In particular, subordinates of the head are all other employees of the company.

To solve achieve an Important Goal we need to form a workgroup. Every person has some efficiency, expressed by a positive integer ai, where i is the person's number. The efficiency of the workgroup is defined as the total efficiency of all the people included in it.

The employees of the big software company are obsessed with modern ways of work process organization. Today pair programming is at the peak of popularity, so the workgroup should be formed with the following condition. Each person entering the workgroup should be able to sort all of his subordinates who are also in the workgroup into pairs. In other words, for each of the members of the workgroup the number of his subordinates within the workgroup should be even.

Your task is to determine the maximum possible efficiency of the workgroup formed at observing the given condition. Any person including the director of company can enter the workgroup.

Input

The first line contains integer n (1 ≤ n ≤ 2·105) — the number of workers of the Big Software Company. 

Then n lines follow, describing the company employees. The i-th line contains two integers pi, ai (1 ≤ ai ≤ 105) — the number of the person who is the i-th employee's immediate superior and i-th employee's efficiency. For the director p1 = - 1, for all other people the condition 1 ≤ pi < i is fulfilled.

Output

Print a single integer — the maximum possible efficiency of the workgroup.

Examples

Input

7
-1 3
1 2
1 1
1 4
4 5
4 3
5 2


Output

17

Note

In the sample test the most effective way is to make a workgroup from employees number 1, 2, 4, 5, 6.
/*Author: Satyajeet Singh, Delhi Technological University*/
    import java.io.*;
    import java.util.*;
    import java.text.*; 
    import java.lang.*;
    import java.math.*;

public class Main{
/*********************************************Constants******************************************/
    static PrintWriter out=new PrintWriter(new OutputStreamWriter(System.out));        
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static long mod=(long)1e9+7;
    static long mod1=998244353;
    static boolean sieve[];
    static ArrayList<Integer> primes;
    static ArrayList<Long> factorial;
    static HashSet<Pair> graph[];
/****************************************Solutions Begins***************************************/
    static long input[],dp[][];
    
    static void dfs(int start,int par){
        long sum=0;
        long min=Long.MAX_VALUE;
        int flag1=0;
        boolean flag2=false;
        for(Pair p:graph[start]){
            if(p.u!=par){
                dfs(p.u,start);
                if(dp[p.u][0]<dp[p.u][1]){
                    flag1=flag1^1;
                }
                else if(dp[p.u][0]==dp[p.u][1]){
                    flag2=true;
                }
                sum+=Math.max(dp[p.u][0],dp[p.u][1]);
                min=Math.min(min,Math.abs(dp[p.u][1]-dp[p.u][0]));
            }
        }
        if(flag2){
            dp[start][1]=sum;
            dp[start][0]=sum;
        }
        else{
            dp[start][flag1]=sum;
            dp[start][flag1^1]=sum-min;
        }
        dp[start][1]=Math.max(dp[start][1],dp[start][0]+input[start]);
        return;
    }
    public static void main (String[] args) throws Exception {
        String st[]=br.readLine().split(" ");
        int n=Integer.parseInt(st[0]);
        Makegraph(n+1);
        input=new long[n+1];
        for(int i=0;i<n;i++){
            st=br.readLine().split(" ");
            int a=Integer.parseInt(st[0]);
            int b=Integer.parseInt(st[1]);
            if(i!=0){
                addEdge(a,i+1,1);
            }
            input[i+1]=b;
        }
        dp=new long[n+1][2];
        dfs(1,1);
        long ans=Math.max(dp[1][1],dp[1][0]);
        out.println(ans);
/****************************************Solutions Ends**************************************************/
        out.flush();
        out.close();
    }

/****************************************Template Begins************************************************/
/***************************************Precision Printing**********************************************/
    static void printPrecision(double d){
        DecimalFormat ft = new DecimalFormat("0.00000000000000000"); 
        out.println(ft.format(d));
    }
/**************************************Bit Manipulation**************************************************/
    static int set(int mask,int bit){
        return (mask|(1<<bit));
    }
    static int unset(int mask,int bit){
        return (mask&(~(1<<bit)));
    }
    static int countBit(int mask){
        int ans=0;
        while(mask!=0){
            if(mask%2==1){
                ans++;
            }
            mask/=2;
        }
        return ans;
    }
    static boolean checkBit(int mask,int bit){
        int a=mask&(1<<bit);
        if(a!=0){
            return true;
        }
        else{
            return false;
        }
    }
    static void printMask(int mask){
        System.out.println(Integer.toBinaryString(mask));
    }
/******************************************Graph*********************************************************/
    static void Makegraph(int n){
        graph=new HashSet[n];
        for(int i=0;i<n;i++){
            graph[i]=new HashSet<>();
        }
    }
    static void addEdge(int a,int b,int c){
        graph[a].add(new Pair(b,c));
    }    
/*********************************************PAIR********************************************************/
    static class PairComp implements Comparator<Pair>{
        public int compare(Pair p1,Pair p2){
            if(p1.u!=p2.u){
                return p1.u-p2.u;
            }
            else{
                return p1.v-p2.v;
            }
        }
    }
    static class Pair implements Comparable<Pair> {
        int u;
        int v;
        int index=-1;
        public Pair(int u, int v) {
            this.u = u;
            this.v = v;
        }
 
        public int hashCode() {
            int hu = (int) (u ^ (u >>> 32));
            int hv = (int) (v ^ (v >>> 32));
            return 31 * hu + hv;
        }
 
        public boolean equals(Object o) {
            Pair other = (Pair) o;
            return u == other.u && v == other.v;
        }
 
        public int compareTo(Pair other) {
            if(index!=other.index)
                return Long.compare(index, other.index);
            return Long.compare(v, other.v)!=0?Long.compare(v, other.v):Long.compare(u, other.u);
        }
 
        public String toString() {
            return "[u=" + u + ", v=" + v + "]";
        }
    }
/******************************************Long Pair*************************************************/
    static class PairCompL implements Comparator<Pairl>{
        public int compare(Pairl p1,Pairl p2){
            long aa=p2.u-p1.u;
            if(aa<0){
                return -1;
            }
            else if(aa>0){
                return 1;
            }
            else{
                return 0;
            }
        }
    }
    static class Pairl implements Comparable<Pair> {
            long u;
            long v;
            int index=-1;
            public Pairl(long u, long v) {
                this.u = u;
                this.v = v;
            }
    
            public int hashCode() {
                int hu = (int) (u ^ (u >>> 32));
                int hv = (int) (v ^ (v >>> 32));
                return 31 * hu + hv;
            }
    
            public boolean equals(Object o) {
                Pair other = (Pair) o;
                return u == other.u && v == other.v;
            }
    
            public int compareTo(Pair other) {
                if(index!=other.index)
                    return Long.compare(index, other.index);
                return Long.compare(v, other.v)!=0?Long.compare(v, other.v):Long.compare(u, other.u);
            }
    
            public String toString() {
                return "[u=" + u + ", v=" + v + "]";
            }
        }
/*****************************************DEBUG***********************************************************/
    public static void debug(Object... o) {
        System.out.println(Arrays.deepToString(o));
    }
/************************************MODULAR EXPONENTIATION***********************************************/
    static long modulo(long a,long b,long c) {
        long x=1;
        long y=a;
        while(b > 0){
            if(b%2 == 1){
                x=(x*y)%c;
            }
            y = (y*y)%c; // squaring the base
            b /= 2;
        }
        return  x%c;
    }
/********************************************GCD**********************************************************/
    static long gcd(long x, long y)
    {
        if(x==0)
            return y;
        if(y==0)
            return x;
        long r=0, a, b;
        a = (x > y) ? x : y; // a is greater number
        b = (x < y) ? x : y; // b is smaller number
        r = b;
        while(a % b != 0)
        {
            r = a % b;
            a = b;
            b = r;
        }
        return r;
    }
/******************************************SIEVE**********************************************************/
    static void sieveMake(int n){
        sieve=new boolean[n];
        Arrays.fill(sieve,true);
        sieve[0]=false;
        sieve[1]=false;
        for(int i=2;i*i<n;i++){
            if(sieve[i]){
                for(int j=i*i;j<n;j+=i){
                    sieve[j]=false;
                }
            }
        }
        primes=new ArrayList<Integer>();
        for(int i=0;i<n;i++){
            if(sieve[i]){
                primes.add(i);
            }
        }        
    }
/********************************************End***********************************************************/
}