#include <cstdio>
#include <iostream>
#include<queue>
#include<string>
#include<math.h>
#include<algorithm>
#include<unordered_map>
using namespace std;


unsigned long long a[200005];
int p[200005];

int main()
{
	unsigned long long n, m, x;
	cin >> n;
	p[0] = -1;
	for (int i = 1; i <= n; ++i)
	{
		cin >> x >> m;
		if (m == 0)
		{
			a[i] = a[p[x]];
			p[i] = p[p[x]];
		}
		else
		{
			a[i] = a[x] + m;
			p[i] = x;
		}
	}
	x = 0;
	for (int i = 1; i <= n; ++i)
		x += a[i];
	cout << x;
    return 0;
}