import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		int n = in.nextInt(), count = 0, t, m;
		int a[][] = new int[n + 1][2];
		a[count][1] = 0;
		a[count][0] = -1;
		count++;
		long sumr = 0;
		for(int i = 0; i < n; i++){
			t = in.nextInt();
			m = in.nextInt();
			if(m == 0){
				a[count][1] = a[a[t][0]][1];
				a[count][0] = a[a[t][0]][0];
			}else{
				a[count][1] = a[t][1] + m;
				a[count][0] = t;
			}
			sumr += a[count][1];
			count++;
		}
		System.out.println(sumr);
	}
}