#include<bits/stdc++.h>
#define int long long
#define ll long long
#define ld long double
#define _1 first
#define _2 second
#define yes cout<<"Yes\n"
#define nah cout<<"No\n"
#define FFF ios_base::sync_with_stdio(0);cin.tie(0);
#define ipr pair<int,int>
#define ret return
#define intt int32_t
#define mid ((l+r)/2)
#define pb push_back
#define lll __int128
using namespace std;
int tst, ts;
intt mo = 0*(998244353)+(1e9+7)*1, dx[] = {0, -1, -1, 0}, dy[] = {1, 1, 2, 0};
int mul( int x, int y ) {
x%=mo;y%=mo;
ret (int) ( (ll) x * y % mo);
ret x*y;
}
int pwo( int x, ll y ) {
int res = 1;
for( int i = 63; i + 1; i-- )
res = mul( res, mul(res , ( ( 1ll << i )&y ? x : 1 )) );
ret res;
}
int dvii( int x, int y ) {
ret mul( x, pwo(y,mo-2) );
}
int oo( char x , char y) {
ret ( int )x - y;
}
int lgg( int x, int y ) {
int u = 0;
while( x ) {
u++;
x /= y;
}
ret u;
}//g++ -Wall -o "%e" "%f" && "./%e"
int mun( int x, int y ) {
while( x < y )x += mo;
ret ( x - y ) % mo;
}
int add( int x, int y ) {
ret x + y - ( mo * ( x + y >= mo ) );
ret x + y;
}
int lcm( int x, int y ) {
if(x*y==0)ret max(x,y);
int o=__gcd(x,y);
x/=o;
ret x*y;
}
#define endl '\n';
#define nl no*2
#define nr no*2+1
const int M =5e4+7, N = 5e5+7, P = 1e12, inf = 1e18+7 ;
int n,a[N],o,s;
vector<int>g[N];
set<ipr>bf[N];
void solve(){
cin>>n>>s;o=s;
for(int i=1;i<=n;i++){
int p;
cin>>a[i]>>p;
g[p].pb(i);
bf[p].insert({a[i],i});
}
set<ipr>st;
st.insert({0,0});
while(st.size()){
ipr p=*st.rbegin();
st.erase(p);
if(p._1>=0){
s+=p._1;
for(auto j:bf[p._2])
st.insert(j);
bf[p._2].clear();
}
else if(p._1+s>0){
int uu=0;
while(bf[p._2].size()){
ipr pr=*bf[p._2].rbegin();
if(p._1>=0)break;
if(s+p._1+pr._1>0){
p._1+=pr._1;uu=1;
for(auto j:bf[pr._2])
bf[p._2].insert(j);
bf[pr._2].clear();
bf[p._2].erase(pr);
}
else break;
}
if(p._1>=0){
s+=p._1;
for(auto j:bf[p._2])
st.insert(j);
bf[p._2].clear();
}
else if(uu)
st.insert(p);
}
else break;
}
cout<<s-o<<endl;
}
intt main() {
FFF
//freopen("7.in", "r", stdin);
//freopen("out.txt", "w", stdout);
tst = 1;
//cin >> tst;
for( ts = 1; ts <= tst; ts++ ){
solve();
}
}
