#include <bits/stdc++.h>
#define ll long long
#define pii pair <int, int>
#define fi first
#define se second
#define pb push_back

using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int N = 5e5+5, M = 5e4+5;
int n, m, k, s, os[N], ck[N], cd;
ll ans;
map <int, int> mp[M];
struct dsu {
	int stk[N<<5], o[N<<5], v[N<<5], ed, d[M], fa[M], c;
	void init (int n) {
		for (int i = 1;i <= n;i++) fa[i] = i;
		c = n;
	}
	inline int find (int x) {
		while (fa[x]^x) x = fa[x];
		return x;
	}
	inline void mer (int x, int y) {
		x = find(x); y = find(y);
		if (x == y) return;
		if (d[x] > d[y]) swap(x, y);
		stk[++ed] = x; o[ed] = 0; v[ed] = fa[x]; fa[x] = y;
		if (d[x] == d[y]) stk[++ed] = y, o[ed] = 1, v[ed] = d[y], d[y]++;
		c--;
	}
	void del (int x) {
		while (ed > x) {
			if (o[ed]) d[stk[ed]] = v[ed];
			else fa[stk[ed]] = v[ed];
			ed--;
		}
	}
}ds, ds2;
struct eg {
	int u, v, w;
}es[N];
vector <int> v[2][N<<2];
void uadd (int p, int l, int r, int tl, int tr, int o, int x) {
	if (tl > tr) return;
	if (tl <= l && r <= tr) return v[o][p].pb(x), void();
	int mid = l+r>>1;
	if (tl <= mid) uadd(p<<1, l, mid, tl, tr, o, x);
	if (tr > mid) uadd(p<<1|1, mid+1, r, tl, tr, o, x);
}
void query (int p, int l, int r) {
	int tc = ds.c, td = ds.ed, tc2 = ds2.c, td2 = ds2.ed;
	for (int x : v[0][p]) {
		ds.mer(es[x].u, es[x].v);
		if (es[x].u != s && es[x].v != s) ds2.mer(es[x].u, es[x].v);
	}
	for (int x : v[1][p]) {
		ds.mer(es[x].u, es[x].v); ds2.mer(es[x].u, es[x].v);
	}
	if (l == r) {
		int o = 1;
		if (ds2.c-1 > k) o = 0;
		if (ds.c > 1) o = 0;
		if (k > ck[l+1]) o = 0;
//		cout << l << " " << o << "\n";
		if (l > m && o == 0) {
			cout << "nonnondayo"; exit(0);
		}
		if (!o) uadd(1, 1, m+1, l+1, m+1, 1, l), k -= (es[l].u == s || es[l].v == s), ans += es[l].w;
	}
	else {
		int mid = l+r>>1;
		query(p<<1, l, mid); query(p<<1|1, mid+1, r);
	}
	ds.c = tc; ds2.c = tc2;
	ds.del(td); ds2.del(td2);
}

signed main () {
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	cin >> n >> m >> k >> s;
	ds.init(n); ds2.init(n); 
	for (int i = 1;i <= m;i++) {
		int u, v, w; cin >> u >> v >> w;
		if (u > v) swap(u, v);
		if (mp[u].count(v)) mp[u][v] = min(mp[u][v], w); else mp[u][v] = w;
		es[i] = (eg){u, v, w};
	}
	m = 0;
	for (int i = 1;i <= n;i++) for (auto j : mp[i]) es[++m] = (eg){i, j.fi, j.se};
	sort(es+1, es+1+m, [&](eg x, eg y) { return x.w > y.w; });
	for (int i = 1;i <= m;i++) {
		os[i] = 1; mp[es[i].u][es[i].v] = 1;
		uadd(1, 1, m+1, 1, i-1, 0, i);
	}
	for (int i = m;i >= 1;i--) ck[i] = ck[i+1]+(es[i].u == s || es[i].v == s);
	query(1, 1, m+1);
	cout << ans;
	return 0;
}