LG4178

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T&x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N=40005;
const int INF=1e9;

int n,m;

int ecnt;
int fir[N],nex[N<<1],to[N<<1],w[N<<1];

inline void addedge(int u,int v,int c){
    nex[++ecnt]=fir[u],fir[u]=ecnt,to[ecnt]=v,w[ecnt]=c;
    nex[++ecnt]=fir[v],fir[v]=ecnt,to[ecnt]=u,w[ecnt]=c;
}

int SIZE,root;
int s[N];
int siz[N];
bool vis[N];
//getroot
void dfs1(int x,int f){
    siz[x]=1;
    s[x]=0;
    for(int i=fir[x];i;i=nex[i]){
        int v=to[i];
        if(v==f||vis[v])continue;
        dfs1(v,x);
        siz[x]+=siz[v];
        s[x]=max(s[x],siz[v]);
    }
    s[x]=max(s[x],SIZE-siz[x]);
    if(s[x]<s[root])root=x;
}
//getdis
int dis[N];
int tot,tmp[N];
void dfs3(int x,int f){
    tmp[++tot]=dis[x];
    for(int i=fir[x];i;i=nex[i]){
        int v=to[i];
        if(v==f||vis[v])continue;
        dis[v]=dis[x]+w[i];
        dfs3(v,x);
    }
}

inline ll calc(int x,int v){
    tot=0;
    dis[x]=v;
    dfs3(x,0);
    sort(tmp+1,tmp+tot+1);
    int l=1,r=tot;
    ll sum=0;
    while(l<r){
        if(tmp[l]+tmp[r]<=m){
            sum+=r-l;
            ++l;
        }
        else --r;
    }
    return sum;
}
ll ans;
//solve
void dfs2(int x){
    ans+=calc(x,0);
    vis[x]=1;
    for(int i=fir[x];i;i=nex[i]){
        int v=to[i];
        if(vis[v])continue;
        ans-=calc(v,w[i]);
        root=0;
        SIZE=siz[v];
        dfs1(v,0);
        dfs2(root);
    }
}

int main(){
//  freopen(".in","r",stdin);
//  freopen(".out","w",stdout);
    r(n);
    for(int i=1;i<n;++i){
        int u,v,w;
        r(u),r(v),r(w);
        addedge(u,v,w);
    }
    r(m);
    s[root]=SIZE=n;
    dfs1(1,0);
    dfs2(root);
    printf("%lld\n",ans);
    return 0;
}