#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
const int maxn = 3 * 1e5 + 7;
const int LOG = 20;
const long long MOD = (long long)(1e9) + 7;
const long long base = 311;
const int ALP_BET = 26;
typedef pair<int, int> ii;
typedef pair<int, long long> il;
typedef pair<long long, int> li;
typedef pair<long long, long long> ll;
int n, m;
long long a[maxn], s;
int p[maxn]; vector<int> adj[maxn];
int root[maxn];
namespace BUFFALO{
const int maxN = 10 + 7;
bool ok[maxN];
int arr[maxN];
long long ans;
void solve(){
for(int i = 1; i <= n; ++i)
arr[i] = i;
ans = s;
do{
memset(ok, false, sizeof(ok));
long long sum = s;
for(int i = 1; i <= n; ++i){
int u = arr[i];
if(p[u] != 0 && !ok[p[u]])
break;
ok[u] = true;
sum = sum + a[u];
if(sum < 0)
break;
ans = max(ans, sum);
}
} while(next_permutation(arr + 1, arr + n + 1));
cout << ans - s << "\n";
return;
}
}
namespace SUB1{
long long dp[maxn];
void dfs(int u){
dp[u] = a[u];
for(int v : adj[u]){
dfs(v);
dp[u] = dp[u] + dp[v];
}
dp[u] = max(dp[u], 0LL);
return;
}
void solve(){
long long ans = 0;
for(int i = 1; i <= m; ++i){
dfs(root[i]);
ans += dp[root[i]];
}
cout << ans << "\n";
return;
}
}
namespace SUB3{
typedef pair<long long, long long> item;
int nn;
item path[maxn];
void dfs(int u, long long ss, long long maxadd, long long maxsub){
ss = ss + a[u];
if(ss > maxadd){
++nn;
path[nn] = {maxsub, ss - maxadd};
maxadd = ss;
}
maxsub = max(maxsub, -ss);
if(!adj[u].empty()){
dfs(adj[u][0], ss, maxadd, maxsub);
}
return;
}
void solve(){
nn = 0;
for(int i = 1; i <= m; ++i){
int u = root[i];
dfs(u, 0, 0, 0);
}
// cerr << nn << "\n";
// for(int i = 1; i <= nn; ++i){
// cerr << path[i].F << " " << path[i].S << "\n";
// }
long long ans = 0;
sort(path + 1, path + nn + 1);
for(int i = 1; i <= nn; ++i){
long long limit = path[i].F, val = path[i].S;
if(limit > s)
break;
ans = ans + val;
}
cout << ans << "\n";
return;
}
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
// freopen("Jobs.INP","r",stdin);
// freopen("Jobs.OUT","w",stdout);
cin >> n >> s; m = 0;
for(int i = 1; i <= n; ++i){
cin >> a[i] >> p[i];
if(p[i] == 0){
++m;
root[m] = i;
} else{
adj[p[i]].push_back(i);
}
}
bool sub1 = true;
long long ss = s;
for(int i = 1; i <= n; ++i) if(a[i] < 0){
ss = ss + a[i];
}
if(ss < 0)
sub1 = false;
// SUBTASK
if(n <= 10){
BUFFALO::solve();
} else
if(sub1){
SUB1::solve();
} else
SUB3::solve();
return 0;
}
