#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<queue>using namespace std;
const int MAXN = 40005;inline int rd() {int x=0,f=1;char ch=getchar();while(!isdigit(ch)) {if(ch=='-') f=-1;ch=getchar();}while(isdigit(ch))  {x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}return x*f;
}int f[MAXN],n,K,sum,mx,siz[MAXN],ans;
int head[MAXN],cnt,stk[MAXN],top,rt;
int to[MAXN<<1],nxt[MAXN<<1],val[MAXN<<1];
queue<int> Q;
bool vis[MAXN];inline void add(int bg,int ed,int w){to[++cnt]=ed,nxt[cnt]=head[bg],val[cnt]=w,head[bg]=cnt;
}inline void update(int x,int w){for(;x<=K;x+=x&-x) f[x]+=w;
}inline int query(int x){int ret=0;for(;x;x-=x&-x) ret+=f[x];return ret;
}void dfs(int x,int fa){siz[x]=1;for(register int i=head[x];i;i=nxt[i]){int u=to[i];if(vis[u] || u==fa) continue;dfs(u,x);siz[x]+=siz[u];}
}void getrt(int x,int fa){int k=0;for(register int i=head[x];i;i=nxt[i]){int u=to[i];if(vis[u] || u==fa) continue;getrt(u,x);k=max(k,siz[u]);}k=max(k,sum-siz[x]);if(k<mx) {mx=k;rt=x;}
}void getdis(int x,int fa,int dis){if(dis<=K){Q.push(dis);stk[++top]=dis;ans+=query(K-dis);}else return;for(register int i=head[x];i;i=nxt[i]){int u=to[i];if(vis[u] || u==fa) continue;getdis(u,x,dis+val[i]);}
}inline void getans(int x){vis[x]=1;for(register int i=head[x];i;i=nxt[i]){int u=to[i];if(vis[u]) continue;getdis(u,x,val[i]);ans+=Q.size();while(!Q.empty()){int now=Q.front();Q.pop();update(now,1);}}for(register int i=1;i<=top;i++) update(stk[i],-1);top=0;for(register int i=head[x];i;i=nxt[i]){int u=to[i];if(vis[u]) continue;dfs(u,x);mx=sum=siz[u];rt=0;getrt(u,x);
//      cout<<u<<" "<<rt<<endl;
        getans(rt);}
}int main() {n=rd();for(register int i=1;i<n;i++) {int x=rd(),y=rd(),z=rd();add(x,y,z);add(y,x,z);}K=rd();sum=mx=n;dfs(1,0);getrt(1,0);getans(rt);cout<<ans<<endl;return 0;
}