#include <bits/stdc++.h>
using namespace std;

const int M = 5e5 + 5;

int n, m, k, s, top, cnt, sum, deg, fa[M], sz[M];
long long ans;
bool hv[M];
pair<int, int> p[M];
map<pair<int, int>, int> mp;

struct E {
    int u, v, w;
} e[M];

bool cmp(E x, E y) { return x.w > y.w; }

vector<E> ad[M * 4];

int find(int u) { return fa[u] == u ? u : find(fa[u]); }

struct A {
    int x, y, xsz, ysz;
    bool xhv, yhv;
} stk[M];

void modify(int p, int l, int r, int a, int b, E t) {
    if (l >= a && r <= b) {
        ad[p].emplace_back(t);
        return;
    }
    int mid = l + r >> 1;
    if (a <= mid) {
        modify(p * 2, l, mid, a, b, t);
    }
    if (b > mid) {
        modify(p * 2 + 1, mid + 1, r, a, b, t);
    }
}

void solve(int p, int l, int r) {
    int cnt_ = cnt, sum_ = sum, deg_ = deg;
    for (auto t : ad[p]) {
        int u = t.u, v = t.v;
        u = find(u);
        v = find(v);
        if (sz[u] < sz[v]) {
            swap(u, v);
        }
        stk[++top] = (A){ .x = u, .y = v, .xsz = sz[u], .ysz = sz[v], .xhv = hv[u], .yhv = hv[v] };
        if (u == v) {
            continue;
        }
        if (u == s) {
            sum += !hv[v];
            hv[v] = 1;
            deg++;
        } else if (v == s) {
            sum += !hv[u];
            hv[u] = 1;
            deg++;
        } else {
            cnt--;
            sum = sum - hv[u] - hv[v] + (hv[u] || hv[v]);
            fa[v] = u;
            sz[u] += sz[v];
            hv[u] |= hv[v];
        }
    }
    if (l == r) {
        if (sum < cnt || cnt > k || deg < k) {
            if (l == m + 1) {
                cout << "nonnondayo\n";
                exit(0);
            }
            modify(1, 1, m + 1, l + 1, m + 1, e[l]);
            ans += e[l].w;
        }
    } else {
        int mid = l + r >> 1;
        solve(p * 2, l, mid);
        solve(p * 2 + 1, mid + 1, r);
    }
    for (int i = 1; i <= ad[p].size(); i++) {
        int u = stk[top].x, v = stk[top].y;
        if (u == v) {
            top--;
            continue;
        }
        if (u == s) {
            hv[v] = stk[top].yhv;
            sum -= !hv[v];
            deg--;
        } else if (v == s) {
            hv[u] = stk[top].xhv;
            sum -= !hv[u];
            deg--;
        } else {
            fa[v] = v;
            sz[u] = stk[top].xsz;
            sz[v] = stk[top].ysz;
            hv[u] = stk[top].xhv;
            hv[v] = stk[top].yhv;
            cnt++;
            sum = sum + hv[u] + hv[v] - (hv[u] || hv[v]);
        }
        top--;
    }
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m >> k >> s;
    for (int i = 1; i <= m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        if (u > v) {
            swap(u, v);
        }
        p[i] = make_pair(u, v);
        if (mp[p[i]] == 0 || mp[p[i]] > w) {
            mp[p[i]] = w;
        }
    }
    sort(p + 1, p + m + 1);
    m = unique(p + 1, p + m + 1) - p - 1;
    for (int i = 1; i <= n; i++) {
        fa[i] = i;
        sz[i] = 1;
    }
    for (int i = 1; i <= m; i++) {
        int u = p[i].first, v = p[i].second, w = mp[p[i]];
        if (u == s || v == s) {
            deg++;
        }
        e[i].u = u;
        e[i].v = v;
        e[i].w = w;
        u = find(u);
        v = find(v);
        if (u == v) {
            continue;
        }
        if (sz[u] < sz[v]) {
            swap(u, v);
        }
        fa[v] = u;
        sz[u] += sz[v];
    }
    sort(e + 1, e + m + 1, cmp);
    for (int i = 2; i <= m; i++) {
        modify(1, 1, m + 1, 1, i - 1, e[i]);
    }
    cnt = n - 1;
    sum = 0;
    deg = 0;
    for (int i = 1; i <= n; i++) {
        fa[i] = i;
        sz[i] = 1;
    }
    solve(1, 1, m + 1);
    cout << ans << '\n';

    return 0;
}