#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll long long
using namespace std;
const int N=4e4+5;
int n,hd[N],xnt,to[N<<1],nxt[N<<1],w[N<<1],f[N<<1],siz[N],ans,mn,rt;
ll dis[N],tis[N],tp[N<<1],tnt,K;
bool vis[N],sj[N];
void add(int x,int y,ll z)
{to[++xnt]=y;nxt[xnt]=hd[x];w[xnt]=z;hd[x]=xnt;to[++xnt]=x;nxt[xnt]=hd[y];w[xnt]=z;hd[y]=xnt;
}
void getrt(int cr,int fa,int s)
{siz[cr]=1;int mx=0;for(int i=hd[cr],v;i;i=nxt[i]) if(!vis[v=to[i]]&&v!=fa){getrt(v,cr,s);siz[cr]+=siz[v];mx=max(mx,siz[v]);}mx=max(mx,s-siz[cr]);if(mx<mn)mn=mx,rt=cr;
}
void add(int x){for(;x<=tnt;x+=(x&-x))f[x]++;}
int query(int x){int ret=0;for(;x;x-=(x&-x))ret+=f[x];return ret;}
void dfs(int cr,int fa,ll lj)
{dis[cr]=lj;sj[cr]=1;for(int i=hd[cr],v;i;i=nxt[i]) if(!vis[v=to[i]]&&v!=fa)dfs(v,cr,lj+w[i]);
}
int calc(int cr,ll w)
{memset(sj,0,sizeof sj);tnt=0;dfs(cr,0,w);for(int i=1;i<=n;i++) if(sj[i]&&dis[i]<=K){tis[i]=K-dis[i];tp[++tnt]=dis[i];tp[++tnt]=tis[i];
//        printf("dis[%d]=%lld tis[%d]=%lld\n",i,dis[i],i,tis[i]);
    }sort(tp+1,tp+tnt+1);tnt=unique(tp+1,tp+tnt+1)-tp-1;int ret=0;for(int i=1;i<=n;i++) if(sj[i]&&dis[i]<=K){dis[i]=lower_bound(tp+1,tp+tnt+1,dis[i])-tp;tis[i]=lower_bound(tp+1,tp+tnt+1,tis[i])-tp;
//        printf("dis[%d]=%lld tis[%d]=%lld\n",i,dis[i],i,tis[i]);ret+=query(tis[i]);add(dis[i]);}memset(f,0,sizeof f);return ret;
}
void solve(int cr,int s)
{
//    printf("rt=%d\n",cr);vis[cr]=1;ans+=calc(cr,0);
//    printf("cr=%d ans=%d\n",cr,ans);for(int i=hd[cr],v;i;i=nxt[i]) if(!vis[v=to[i]]){ans-=calc(v,w[i]);int ts=(siz[cr]>siz[v]?siz[v]:s-siz[cr]);//-siz[cr]!!!mn=N;getrt(v,0,ts);solve(rt,ts);}
}
int main()
{scanf("%d",&n);int x,y;ll z;for(int i=1;i<n;i++){scanf("%d%d%lld",&x,&y,&z);add(x,y,z);}scanf("%lld",&K);mn=N;getrt(1,0,n);solve(rt,n);printf("%d\n",ans);return 0;
}