/**************************************************************    Problem: 1468    User: BeiYu    Language: C++    Result: Accepted    Time:832 ms    Memory:3804 kb****************************************************************/ #include<cstdio>#include<utility>#include<vector>#include<queue>#include<algorithm>#include<iostream>using namespace std; typedef pair< int,int > pr;#define mpr make_pair#define debug(a) cout<<#a<<"="<<a<<" "const int N = 40005; int n,m,k,rt,sz,ans;vector<pr> g[N];int s[N],f[N],b[N];vector<int> d;int q[N],h,t; inline int in(int x=0,char ch=getchar()){ while(ch>‘9‘ || ch<‘0‘) ch=getchar();    while(ch>=‘0‘ && ch<=‘9‘) x=(x<<3)+(x<<1)+ch-‘0‘,ch=getchar();return x; }void GetRoot(int u,int fa){    s[u]=1,f[u]=0;    for(int i=0,v;i<g[u].size();i++) if((v=g[u][i].first)!=fa && !b[v]){        GetRoot(v,u),s[u]+=s[v],f[u]=max(f[u],s[v]);    }f[u]=max(f[u],sz-s[u]);if(f[u]<f[rt]) rt=u;}void GetDeep(int u,int fa,int dep){    d.push_back(dep),s[u]=1;    for(int i=0,v;i<g[u].size();i++) if((v=g[u][i].first)!=fa && !b[v])        GetDeep(v,u,dep+g[u][i].second),s[u]+=s[v];}int Calc(int u,int w){    d.clear(),GetDeep(u,u,w);    sort(d.begin(),d.end());    int res=0;    for(int l=0,r=d.size()-1;l<r;) if(d[l]+d[r]<=k) res+=r-l,l++;else r--;    return res;}void GetAns(int u){    ans+=Calc(u,0);b[u]=1;    for(int i=0,v;i<g[u].size();i++) if(!b[v=g[u][i].first])         ans-=Calc(v,g[u][i].second),f[0]=sz=s[v],GetRoot(v,rt=0),GetAns(rt);}int main(){//  freopen("in.in","r",stdin);    n=in();    for(int i=1,u,v,w;i<n;i++) u=in(),v=in(),w=in(),g[u].push_back(mpr(v,w)),g[v].push_back(mpr(u,w));    k=in();    f[rt=0]=sz=n;    GetRoot(1,0);    GetAns(rt);    cout<<ans<<endl;    return 0;}