#include<bits/stdc++.h>
#define sqr(x) ((x)*(x))
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define ld long double
#define vi vector<int>
#define all(a) a.begin(),a.end()
#define HEAP(...) priority_queue<__VA_ARGS__ >
#define heap(...) priority_queue<__VA_ARGS__,vector<__VA_ARGS__ >,greater<__VA_ARGS__ > > 
#define pii pair<int,int> 
#define pb push_back
#define mp make_pair
#define debuge cerr<<"isok"<<endl
#define debug(x) cerr<<#x<<"="<<x<<endl
#define dprintf(...) fprintf(stderr,__VA_ARGS__)
#define SS second
#define FF first
#define ls (k<<1)
#define rs (k<<1|1)
#define clr(a,x) memset(a,x,sizeof(a))
#define cpy(a,x) memcpy(a,x,sizeof(a))
#define file(x) freopen(x".in","r",stdin),freopen(x".out","w",stdout)
#define SZ(x) ((int)x.size())
using namespace std;
template<class T> inline void gmin(T &x,const T &y){x=x>y?y:x;}
template<class T> inline void gmax(T &x,const T &y){x=x<y?y:x;}
template<class T> inline bool Gmin(T &x,const T &y){return x>y?x=y,1:0;}
template<class T> inline bool Gmax(T &x,const T &y){return x<y?x=y,1:0;}
const int BufferSize=1<<16;
char buffer[BufferSize],*Bufferhead,*Buffertail;
bool Terminal;
inline char Getchar(){
	if(Bufferhead==Buffertail){
		int l=fread(buffer,1,BufferSize,stdin);
		if(!l){Terminal=1;return 0;}
		Buffertail=(Bufferhead=buffer)+l;
	}
	return *Bufferhead++;
}
template<class T>inline bool read(T &x){
	x=0;char c=Getchar(),rev=0;
	while(c<'0'||c>'9'){rev|=c=='-';c=Getchar();if(Terminal)return 0;}
	while(c>='0'&&c<='9') x=x*10+c-'0',c=Getchar();
	if(c=='.'){
		c=Getchar();double t=0.1;
		while(c>='0'&&c<='9') x=x+(c-'0')*t,c=Getchar(),t=t/10;
	}
	x=rev?-x:x;
	return 1;
}
template<class T1,class T2> inline bool read(T1 &x,T2 &y){return read(x)&read(y);}
template<class T1,class T2,class T3> inline bool read(T1 &x,T2 &y,T3 &z){return read(x)&read(y)&read(z);}
template<class T1,class T2,class T3,class T4> inline bool read(T1 &x,T2 &y,T3 &z,T4 &w){return read(x)&read(y)&read(z)&read(w);}
inline bool reads(char *x){
	char c=Getchar();
	while(c<33||c>126){c=Getchar();if(Terminal)return 0;}
	while(c>=33&&c<=126) (*x++)=c,c=Getchar();
	*x=0;return 1;
}
template<class T>inline void print(T x,const char c='\n'){
	if(!x){putchar('0');putchar(c);return;}
	if(x<0) putchar('-'),x=-x;
	int m=0,a[20];
	while(x) a[m++]=x%10,x/=10;
	while(m--) putchar(a[m]+'0');
	putchar(c);
}
//--------------------------------head---------------------------------------------

const ll inf=0x3f3f3f3f;
const int N=52,M=100005,mod=1e9+7;
template<class T,class S> inline void ch(T &x,const S y){x=(x+y)%mod;}
inline int exp(int x,int y,const int mod=::mod){
	int ans=1;
	while(y){
		if(y&1) ans=(ll)ans*x%mod;
		x=(ll)x*x%mod;y>>=1;
	}return ans;
}

int n,X,D,v[N],w[N],par[N],si[N],si2[N],rk[N];
ll dp[2][N*N*N];

inline ll get(int i,int j){
	return dp[i-1&1][j]-(ll)w[i]*(j/v[i]);
}
inline int solve(int m){
	if(m<0) return -inf;
	int ans=0;
	for(int i=1;i<=n;i++){
		int j=rk[i],t=min(si2[j],m/w[j]);
		m-=t*w[j];ans+=t*v[j];
	}
	return ans;
}

int main(){
#ifdef rqgao2014
	assert(freopen("input.txt","r",stdin));
#endif
	scanf("%d%d%d",&n,&X,&D);
	scanf("%d",&w[1]);v[1]=1;
	for(int i=2;i<=n;i++)
		scanf("%d%d",&w[i],&par[i]),v[i]=1;
	si2[1]=inf;si[1]=n;
	for(int i=2;i<=n;i++) si2[i]=max(0,D-n),si[i]=min(D,n);
	for(int i=n;i;i--)
		w[par[i]]=min(X+1,w[i]+w[par[i]]),v[par[i]]+=v[i];
	for(int i=1;i<=n;i++)
		dprintf("%d %d\n",w[i],v[i]);
	for(int i=1;i<=n;i++)
		rk[i]=i;
	sort(rk+1,rk+n+1,[&](int x,int y){return (ll)v[x]*w[y]>(ll)v[y]*w[x];});
	for(int i=0;i<=n*n*n;i++)
		dp[0][i]=dp[1][i]=inf;
	dp[0][0]=0;
	int ans=0;
	for(int i=1,sum=0;i<=n;i++){
		int ts=sum;sum+=si[i]*v[i];
		static int h[N],t[N],q[N][N*N*N];
		for(int j=0;j<v[i];j++)
			h[j]=1,t[j]=0;
		for(int j=0;j<=sum;j++){
			int k=j%v[i];
			while(h[k]<=t[k]&&q[k][h[k]]<j-v[i]*si[i]) h[k]++;
			while(h[k]<=t[k]&&get(i,q[k][t[k]])>get(i,j)) t[k]--;
			q[k][++t[k]]=j;
			dp[i&1][j]=min(inf,dp[i-1&1][q[k][h[k]]]+(ll)w[i]*(j-q[k][h[k]])/v[i]);
//			dp[i&1][j]=inf;
//			for(int k=0;k<=si[i]&&k<=j/v[i];k++)
//				gmin(dp[i&1][j],dp[i-1&1][j-k*v[i]]+(ll)w[i]*k);
		}
		if(i==n){
			for(int j=0;j<=sum;j++)
				gmax(ans,j+solve(X-dp[i&1][j]));
		}
	}
	printf("%d\n",ans);
	return 0;
}

Measured memory_bytes: 30848