#include<unordered_map>
#include<functional>
#include<algorithm>
#include<windows.h>
#include<iostream>
#include<cassert>
#include<cstring>
#include<cstdlib>
#include<numeric>
#include<iomanip>
#include<bitset>
#include<random>
#include<cstdio>
#include<string>
#include<vector>
#include<array>
#include<ctime>
#include<stack>
#include<queue>
#include<cmath>
#include<set>
#include<map>

#define fi first
#define se second
#define pii pair<int,int>
#define NO cout << "NO\n"
#define YES cout << "YES\n"
#define stop system("pause");
#define debug printf("++ ++\n");
#define cout(a) cout << (#a) << " = " << a << endl;
using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int N = 3e5;
random_device gen;
mt19937 rnd(gen());
int n, m;
int dis1[N + 5], disn[N + 5];
vector<array<int, 3> > e;
vector<pii > G[N + 5];

/* 终点是一切概率的结束，也是一切期望的开始 */
/* *
 * 可能做法: 基础算法(思维, 暴力, 贪心) / 图论
 * */

struct DSU {
	std::vector<int> pre, sz;

	DSU(int n) : pre(n + 1), sz(n + 1, 1) {
		std::iota(pre.begin(), pre.end(), 0ll);
	}

	int find(int x) {
		return pre[x] == x ? x : pre[x] = find(pre[x]);
	}

	int size(int x) {
		return sz[find(x)];
	}

	bool same(int x, int y) {
		return find(x) == find(y);
	}

	bool merge(int x, int y) {
		int fx = find(x), fy = find(y);
		if (fx == fy) return false;
		if (sz[fx] > sz[fy]) swap(fx, fy);
		sz[fy] += sz[fx];
		pre[fx] = fy;
		return true;//合并成功
	}

};

void dfs(int father, int u, int tmp, int dis[]) {
	dis[u] = tmp;
	for (auto [v, w] : G[u]) {
		if (v == father) continue;
		dfs(u, v, max(tmp, w), dis);
	}
}


void solve() {
	cin >> n >> m;
	DSU dsu(n);
	for (int i = 1, u, v, w; i <= m; i++) {
		cin >> u >> v >> w;
		e.push_back({u, v, w});
	}
	std::sort(e.begin(), e.end(), [&](const array<int, 3> a, const array<int, 3> b) {
		return a.at(2) < b.at(2);
	});
	for (auto [u, v, w] : e) {
		if (dsu.same(u, v)) continue;
		dsu.merge(u, v);
		G[u].emplace_back(v, w);
		G[v].emplace_back(u, w);
	}
	dfs(0, 1, 0, dis1);
	dfs(0, n, 0, disn);
	int ans = INF;
	for (auto [u, v, w] : e) { //枚举最大边, 消除同侧影响
		int uw = dis1[u], vw = disn[v];
		if (w >= max(uw, vw)) ans = min(ans, max(uw, vw) + w);
		uw = disn[u], vw = dis1[v];
		if (w >= max(uw, vw)) ans = min(ans, max(uw, vw) + w);
	}
	cout << ans << '\n';
}

signed main() {
	std::ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
	int t = 1;
//	cin >> t;
	while (t--) solve();
	return 0;
}

answer.code:4:9: fatal error: windows.h: No such file or directory
    4 | #include<windows.h>
      |         ^~~~~~~~~~~
compilation terminated.