#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#define N 500000
using namespace std;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
struct reads
{
	int x,y,z;
	bool operator < (const reads &t)const
	{
		return z>t.z;	
	}
};
reads st[N+1];
struct node
{
	int x,y,d;
};
node dque[N+1],dque2[N+1];
int n,m,sk,s,top,top2,rt[N+1],rt2[N+1],rk[N+1],rk2[N+1],cnt,cnt2,cnt3;
long long ans;
int find(int x)
{
	if (rt[x]==x) return x;
	return find(rt[x]);
}
void unionn(int x,int y)
{
	if (rk[x]>rk[y]) swap(x,y);
	dque[++top]=(node){x,y,rk[y]},rk[y]=max(rk[y],rk[x]+1),rt[x]=y,cnt--;
	return;
}
void undo()
{
	rt[dque[top].x]=dque[top].x,rk[dque[top].y]=dque[top].d,top--,cnt++;
	return;
}
int find2(int x)
{
	if (rt2[x]==x) return x;
	return find2(rt2[x]);
}
void unionn2(int x,int y)
{
	if (rk2[x]>rk2[y]) swap(x,y);
	dque2[++top2]=(node){x,y,rk2[y]},rk2[y]=max(rk2[y],rk2[x]+1),rt2[x]=y,cnt2--;
	return;
}
void undo2()
{
	rt2[dque2[top2].x]=dque2[top2].x,rk2[dque2[top2].y]=dque2[top2].d,top2--,cnt2++;
	return;
}
struct seg
{
	struct node
	{
		int l,r;
		vector<reads>p;
	};
	node tree[(N<<2)+1];
	void build(int k,int l,int r)
	{
		tree[k].l=l,tree[k].r=r;
		if (l==r) return;
		int mid=(l+r)>>1;
		build(k<<1,l,mid),build(k<<1|1,mid+1,r);
		return;
	}
	void add(int k,int l,int r,reads d)
	{
		if (tree[k].l==l&&tree[k].r==r)
		{
			tree[k].p.push_back(d);
			return;
		}
		int mid=(tree[k].l+tree[k].r)>>1;
		if (r<=mid) add(k<<1,l,r,d);
		else if (l>=mid+1) add(k<<1|1,l,r,d);
		else add(k<<1,l,mid,d),add(k<<1|1,mid+1,r,d);
		return;
	}
	void solve(int k)
	{
		int rst=0,rst2=0,rst3=0;
		for (int i=0;i<tree[k].p.size();++i)
		{
			if (find(tree[k].p[i].x)!=find(tree[k].p[i].y)) unionn(find(tree[k].p[i].x),find(tree[k].p[i].y)),rst++;
			if (tree[k].p[i].x!=s&&tree[k].p[i].y!=s&&find2(tree[k].p[i].x)!=find2(tree[k].p[i].y)) unionn2(find2(tree[k].p[i].x),find2(tree[k].p[i].y)),rst2++;
			if (tree[k].p[i].x==s||tree[k].p[i].y==s) cnt3++,rst3++;
		}
		if (tree[k].l==tree[k].r)
		{
			if (cnt!=1||cnt2>sk||cnt3<sk)
			{
				if (!tree[k].l)
				{
					puts("nonnondayo");
					exit(0);
				}
				else
				{
					ans+=st[tree[k].l].z;
					if (tree[k].l!=m) add(1,tree[k].l+1,m,st[tree[k].l]);
				}
			}
			for (int i=1;i<=rst;++i) undo();
			for (int i=1;i<=rst2;++i) undo2();
			cnt3-=rst3;
			return;
		}
		solve(k<<1),solve(k<<1|1);
		for (int i=1;i<=rst;++i) undo();
		for (int i=1;i<=rst2;++i) undo2();
		cnt3-=rst3;
		return;
	}
};
seg T;
int main()
{
	cnt=n=read(),cnt2=n-1,m=read(),sk=read(),s=read(),T.build(1,0,m);
	for (int i=1;i<=n;++i) rt[i]=rt2[i]=i;
	for (int i=1;i<=m;++i) st[i].x=read(),st[i].y=read(),st[i].z=read();
	sort(st+1,st+m+1);
	for (int i=1;i<=m;++i) T.add(1,0,i-1,st[i]);
	T.solve(1),printf("%lld\n",ans);
	return 0;
}