#include <bits/stdc++.h>
// #include <bits/extc++.h>
// #pragma GCC optimize("Ofast,unroll-loops,O3")
// #pragma GCC target("avx,avx2,fma")
using namespace std;
// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
// template <typename T>
// using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
// template <typename T>
// using ordered_multiset = tree <T, null_type, less_equal <T>, rb_tree_tag, tree_order_statistics_node_update>;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using uint = unsigned int;
using i128 = __int128_t;
istream& operator>>(istream& is, i128& x) {
long long a;
is >> a;
x = (i128) a;
return is;
}
ostream& operator<<(ostream& os, i128& x) {
long long a = (long long) x;
os << a;
return os;
}
template <typename T>
ostream& operator<<(ostream& is, vector <T>& a) {
for (uint i = 0; i < a.size(); ++i) is << a[i] << " ";
return is;
}
#ifdef LOCAL
# define DEBUG(x) cerr << "(" << __LINE__ << ") " << #x << ": " << x << endl;
#else
# define DEBUG(x)
#endif
const ll inf = 1e18 + 1e16;
const int inf_t = 1e9 + 7;
const ll mod = 1e9 + 7;
#define int long long
const int MAXN = 300001;
vector <int> g[MAXN];
int n;
vector <int> x;
vector <priority_queue <pair <int, int>, vector <pair <int, int>>, greater <pair <int, int>>>> dp;
void dfs(int v) {
for (int u : g[v]) {
dfs(u);
}
for (int u : g[v]) {
if (dp[u].size() > dp[v].size()) swap(dp[v], dp[u]);
}
for (int u : g[v]) {
while (!dp[u].empty()) {
dp[v].push(dp[u].top());
dp[u].pop();
}
}
int req = -x[v];
int s = x[v];
while (!dp[v].empty() && (s <= 0 || req > dp[v].top().first)) {
req = max(req, dp[v].top().first - s);
s += dp[v].top().second;
dp[v].pop();
}
if (s > 0) dp[v].push(make_pair(req, s));
}
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin >> n;
int s;
cin >> s;
x.resize(n + 1);
for (int i = 1; i <= n; ++i) {
cin >> x[i];
int p;
cin >> p;
g[p].push_back(i);
}
dp.resize(n + 1);
dfs(0);
int ans = 0;
while (!dp[0].empty()) {
if (s >= dp[0].top().first) {
ans += dp[0].top().second;
s += dp[0].top().second;
dp[0].pop();
} else {
break;
}
}
cout << ans;
}
