//chockolateman
#include<bits/stdc++.h>
using namespace std;
const long long INF = 1000000000000000000ll;
long long N,a[300005],par[300005],prof[300005],d[300005],tin[300005],tout[300005],timer,rev_tin[300005];
long long S,ans;
bool used[300005];
vector<long long> adj[300005];
struct Node
{
long long unactive,pos1,active,pos2,prof,lazy = 0; //ret.unactive = needed to pass, ret.active = max_active score
}st[1200005];
void dfs(long long v,long long p)
{
tin[v] = ++timer;
rev_tin[tin[v]] = v;
prof[tin[v]] = prof[tin[p]] + a[v];
d[tin[v]] = min(d[tin[p]],prof[tin[v]]);
for(auto u : adj[v])
if(u != p)
dfs(u,v);
tout[v] = timer;
}
Node combine(Node left,Node right)
{
Node ret;
if(left.pos1==0)
{
ret.unactive = right.unactive;
ret.pos1 = right.pos1;
}
else if(right.pos1==0)
{
ret.unactive = left.unactive;
ret.pos1 = left.pos1;
}
else if(left.unactive >= right.unactive)
{
ret.unactive = left.unactive;
ret.pos1 = left.pos1;
}
else
{
ret.unactive = right.unactive;
ret.pos1 = right.pos1;
}
if(left.pos2==0)
{
ret.active = right.active;
ret.pos2 = right.pos2;
}
else if(right.pos2==0)
{
ret.active = left.active;
ret.pos2 = left.pos2;
}
else if(left.active >= right.active)
{
ret.active = left.active;
ret.pos2 = left.pos2;
}
else
{
ret.active = right.active;
ret.pos2 = right.pos2;
}
return ret;
}
void build(long long v = 1,long long start = 1,long long end = N)
{
if(start==end)
{
if(d[start] + S >= 0)
{
st[v].unactive = - INF;
st[v].pos1 = 0;
st[v].active = prof[start];
st[v].pos2 = start;
st[v].prof = prof[start];
st[v].lazy = 0;
}
else
{
st[v].unactive = d[start];
st[v].pos1 = start;
st[v].active = -INF;
st[v].pos2 = 0;
st[v].prof = prof[start];
st[v].lazy = 0;
}
return;
}
long long mid = (start + end)/2;
build(2*v,start,mid);
build(2*v+1,mid+1,end);
st[v] = combine(st[2*v],st[2*v+1]);
}
void propagate(long long v,long long start,long long end);
void update(long long l,long long r,long long val,long long v = 1,long long start = 1,long long end = N)
{
if(start==l && end==r)
{
st[v].unactive += val;
st[v].active += val;
st[v].prof += val;
st[v].lazy += val;
return;
}
propagate(v,start,end);
long long mid = (start + end)/2;
if(r <= mid)
update(l,r,val,2*v,start,mid);
else if(l > mid)
update(l,r,val,2*v+1,mid+1,end);
else
{
update(l,mid,val,2*v,start,mid);
update(mid+1,r,val,2*v+1,mid+1,end);
}
st[v] = combine(st[2*v],st[2*v+1]);
}
void propagate(long long v,long long start,long long end)
{
if(st[v].lazy)
{
long long mid = (start + end)/2;
update(start,mid,st[v].lazy,2*v,start,mid);
update(mid+1,end,st[v].lazy,2*v+1,mid+1,end);
st[v].lazy = 0;
}
}
void active(long long pos,long long v = 1,long long start = 1,long long end = N)
{
if(start==end)
{
st[v].unactive = - INF;
st[v].pos1 = 0;
st[v].active = st[v].prof;
st[v].pos2 = start;
return;
}
propagate(v,start,end);
long long mid = (start + end)/2;
if(pos <= mid)
active(pos,2*v,start,mid);
else
active(pos,2*v+1,mid+1,end);
st[v] = combine(st[2*v],st[2*v+1]);
}
void deactive(long long pos,long long v = 1,long long start = 1,long long end = N)
{
if(start==end)
{
st[v].unactive = - INF;
st[v].pos1 = 0;
st[v].active = - INF;
st[v].pos2 = 0;
return;
}
propagate(v,start,end);
long long mid = (start + end)/2;
if(pos <= mid)
deactive(pos,2*v,start,mid);
else
deactive(pos,2*v+1,mid+1,end);
st[v] = combine(st[2*v],st[2*v+1]);
}
void use(long long v)
{
if(used[v])
return;
used[v] = true;
S += a[v];
ans += a[v];
deactive(tin[v]);
update(tin[v],tout[v],-a[v]);
use(par[v]);
}
int main()
{
scanf("%lld%lld",&N,&S);
for(long long p,i = 1 ; i <= N ; i++)
{
scanf("%lld%lld",&a[i],&p);
par[i] = p;
if(p==0)
par[i] = i;
else
{
adj[p].push_back(i);
adj[i].push_back(p);
}
}
for(long long i = 1 ; i <= N ; i++)
if(par[i]==i)
dfs(i,i);
build();
bool moved = true;
while(moved)
{
moved = false;
if(st[1].pos2 > 0 && st[1].active >= 0)
{
moved = true;
use(rev_tin[st[1].pos2]);
}
while(st[1].pos1 > 0 && st[1].unactive + S >= 0)
{
moved = true;
active(st[1].pos1);
}
}
printf("%lld\n",ans);
return 0;
}
