#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
#define ll long long
ll mod = 998244353;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll binpow(ll a, ll b)
{
ll res = 1;
while (b>0)
{
if (b&1)
res = (res*a)%mod;
a = (a*a)%mod;
b>>=1;
}
return res;
}
ll gcd(ll x, ll y)
{
if (y==0)
return x;
return gcd(y, x%y);
}
ll maxi = 303030;
vector<vector<ll>>g(maxi);
vector<ll>v(maxi), vis(maxi, 0);
map<ll,ll>mp;
ll dfs(ll x)
{
vis[x] = 1;
ll val = v[x];
for (auto i:g[x])
{
if (vis[i]==0)
{
val += max(0ll, dfs(i));
}
}
return val;
}
void solve()
{
ll n,s;
cin>>n>>s;
for (int i=1 ; i<=n ;i++)
{
cin>>v[i];
ll x;
cin>>x;
if (x!=0)
{
g[x].push_back(i);
g[i].push_back(x);
}
}
ll res = 0;
for (int i=1 ; i<=n ; i++)
{
if (vis[i]==0) res += dfs(i);
}
cout<<res<<endl;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ll tt = 1;
// cin>>tt;
while (tt--)
{
solve();
}
return 0;
}
