//Proud of You//
#include <bits/stdc++.h>
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
using namespace std;
const int N = 3e5 + 17;
int n, a[N], c[N];
bool ex[N];
long long s, f[N];
vector <int> adj[N];
priority_queue <pair <int, int>> pq;
inline void dfs (int u, long long sm)
{
f[u] = a[u];
for (int v: adj[u])
{
dfs (v, sm + a[u]);
if (f[v] > 0)
{
f[u] += f[v];
}
}
if (sm + f[u] > 0)
{
ex[u] = 1;
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> s;
for (int i = 1, j; i <= n; ++i)
{
cin >> a[i] >> j;
if (j)
{
adj[j].push_back(i);
++c[i];
}
}
for (int i = 1; i <= n; ++i)
{
if (!c[i])
{
dfs (i, 0);
if (ex[i])
{
pq.push ({a[i], i});
}
}
}
long long ans = s, z = 0;
while (!pq.empty())
{
auto [au, u] = pq.top();
pq.pop();
if (s + z + au < 0)
{
continue;
}
z += au, ans = max (ans, z);
for (int v: adj[u])
{
--c[v];
if (!c[v] && ex[v])
{
pq.push ({a[v], v});
}
}
}
cout << ans;
}
