#include<bits/stdc++.h>

#define vc vector
#define pb emplace_back
#define pii pair<int, int>
#define mkp make_pair
#define rep(i, a, b) for(int i = (a); i <= (b); ++i)
#define lep(i, a, b) for(int i = (a); i >= (b); --i)

#define int long long

using namespace std;

inline int read() {
	int x = 0, w = 0; char ch = getchar(); while(!isdigit(ch)) w |= (ch == '-'), ch = getchar();
	while(isdigit(ch)) x = x * 10 + (ch ^ 48), ch = getchar(); return w ? -x : x; 
}

const int N = 1e6 + 5, P = 1e9 + 7, inf = 0x3f3f3f3f3f3f3f3f;

inline void chkmin(int &x, int y) { x = x > y ? y : x; }
inline void inc(int &x, int y) { x += y - P; x += (x >> 31) & P; }
inline int power(int a, int b) { int res = 1; for(; b; b >>= 1, a = 1ll * a * a % P) if(b & 1) res = 1ll * res * a % P; return res; }
inline int inv(int x) { return power(x, P - 2); }

int n, m, k, s, ans, anc[N], val[N], key[N];
struct edge { int u, v, w; bool friend operator<(edge A, edge B) { return A.w < B.w; } };
vc<edge> e;
vc<int> all;

inline int get(int x) { return anc[x] == x ? x : anc[x] = get(anc[x]); }
inline void merge(int x, int y, int z) {
	x = get(x); y = get(y);
	if(x == y) return ;
	if(val[x] > val[y]) swap(x, y);
	anc[y] = x; key[y] = z; ans += z;
}

signed main() {
	n = read(); m = read(); k = read(); s = read();
	rep(i, 1, n) anc[i] = i, val[i] = inf, key[i] = -1;
	for(int i = 1, u, v, w; i <= m; i++) {
		u = read(); v = read(); w = read();
		if(u == s) chkmin(val[v], w);
		else if(v == s) chkmin(val[u], w);
		else e.pb(edge{u, v, w});
	}
	
	sort(e.begin(), e.end());
	for(int i = 0; i < e.size(); i++) 
		merge(e[i].u, e[i].v, e[i].w);
	
	rep(i, 1, n) if(i != s && get(i) == i) {
		if(val[i] == inf) return puts("nonnondayo"), 0;
		--k; ans += val[i]; val[i] = inf;
	}
	if(k < 0) return puts("nonnondayo"), 0;
	
	vc<int> ex;
	rep(i, 1, n) if(i != s && val[i] != inf) 
		ex.pb(val[i] - key[i]);
	if(ex.size() < k) return puts("nonnondayo"), 0;
	sort(ex.begin(), ex.end());
	rep(i, 0, k - 1) ans += ex[i];
	
	cout << ans << endl;
	return 0;
}