#include #define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++) using namespace std; typedef long long ll; template struct Graph { struct edge { int to; T cost; }; int N; vector> G; vector dist; vector prever; Graph(int n) { init(n); } T inf() { if (is_same_v) return 1e9; else return 1e18; } T zero() { return T(0); } void init(int n) { N = n; G.resize(N); dist.resize(N, inf()); } void add_edge(int s, int t, T cost) { edge e; e.to = t, e.cost = cost; G[s].push_back(e); } void dijkstra(int s) { rep(i, 0, N) dist[i] = inf(); prever = vector(N, -1); dist[s] = zero(); priority_queue, vector>, greater>> q; q.push({zero(), s}); while (!q.empty()) { int now; T nowdist; tie(nowdist, now) = q.top(); q.pop(); if (dist[now] < nowdist) continue; for (auto e : G[now]) { T nextdist = nowdist + e.cost; // 次の頂点への距離 if (dist[e.to] > nextdist) { prever[e.to] = now; dist[e.to] = nextdist; q.push({dist[e.to], e.to}); } } } } void bfs01(int s) { rep(i, 0, N) dist[i] = inf(); prever = vector(N, -1); dist[s] = zero(); deque q; q.push_back(s); while (!q.empty()) { int now = q.front(); q.pop_front(); for (auto e : G[now]) { T nextdist = dist[now] + e.cost; if (dist[e.to] > nextdist) { prever[e.to] = now; dist[e.to] = nextdist; if (e.cost == zero()) q.push_front(e.to); else q.push_back(e.to); } } } } vector get_path(int t) { // tへの最短路構築 if (dist[t] >= inf()) return {-1}; vector path; for (; t != -1; t = prever[t]) { path.push_back(t); } reverse(path.begin(), path.end()); return path; } }; void solve() { int n, m, k; cin >> n >> m >> k; vector u(m), v(m), c(m); rep(i, 0, m) { cin >> u[i] >> v[i] >> c[i]; u[i]--, v[i]--; } int q = 1; while (q--) { int s = 0, t = n - 1; auto check = [&](ll mid) { // ([...,1,1,1,0,0,0,...]) Graph gr(n); rep(i, 0, m) { if (c[i] > mid) { gr.add_edge(u[i], v[i], 1); gr.add_edge(v[i], u[i], 1); } else { gr.add_edge(u[i], v[i], 0); gr.add_edge(v[i], u[i], 0); } } gr.bfs01(s); return gr.dist[t] >= k; }; auto binary = [&]() { // ll ll L = -1, R = 1; // 解[L,R) 探索範囲(L,R) while (check(R)) R *= 2; ll mid = L + (R - L) / 2; while (R - L > 1) { if (check(mid)) L = mid; else R = mid; mid = L + (R - L) / 2; } return R; // L-true R-false }; cout << binary() << ' '; } cout << '\n'; } int main() { cin.tie(0); cout.tie(0); ios::sync_with_stdio(0); solve(); }