#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#define NMAX 100003
using namespace std;
int table, n, p[NMAX], s, sol[NMAX], sum[NMAX];
vector <int> v[NMAX];
void dfs(int k)
{
    sol[k] = sum[k];
    for (int i = 0; i < v[k].size(); i++)
    {
        dfs(v[k][i]);
        p[i] = sol[v[k][i]];
    }
    sort(p, p + v[k].size());
    int i = 0;
    while ( sol[k] + p[i] <=s && i < v[k].size())
    {
        
        table++;
        sol[k] += p[i];
        i++;
    }
}
int main ()
{
    ifstream cin ("mese.in");
    ofstream cout ("mese.out");
    cin >> n >> s;
    int x;
    for (int i = 1;i <= n;i ++)
    {
        cin >> x >> sum[i];
        v[x].push_back (i);
    }
    dfs(0);
    cout <<n + 1 -  table;
    return 0;
}