#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#define NMAX 100004
using namespace std;
int  p[NMAX], sum[NMAX], n, s,table;
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]);
    for(int i = 0; i < v[k].size(); i++)
        p[i] = sum[v[k][i]];
    sort (p, p + v[k].size());
    for(int i = 0; i <v[k].size(); i++)
    {
        if (sum[k] + p[i] <= s)
        {
            sum[k] += p[i];
            table++;
        }
        else break;
    }
}
using namespace std;
int main()
{
    int x;
    ifstream cin ("mese.in");
    ofstream cout ("mese.out");
    cin >> n >> s;
    for (int i = 1; i <= n; i++)
    {
        cin >> x >> sum[i];
        v[x].push_back(i);
    }
    dfs(0);
    cout << n + 1 - table;
}