#include <bits/stdc++.h>
using namespace std ;
const int N = 3e5 + 5, M = 1e6 + 5 ;
using ll = long long ;

int n, m ;
int fa[N] ;
int L[M], R[M], w[M] ;
int id[M], val[N], val2[N] ;

int get(int x) { return x == fa[x] ? x : x = fa[x] = get(fa[x]) ; }

void merge(int x, int y)
{
	int l = get(x), r = get(y) ;
	if(l != r) fa[r] = l ;
}

bool isMerge(int x, int y)
{
	int l = get(x), r = get(y) ;
	return l == r ;
}

vector<pair<int, int>> g[N] ;

int pre[N], go[N] ;
bool in[M] ;

void dfs(int x, int f)
{
	for(auto [y, z] : g[x]) if(y != f)
	{
		pre[y] = z ; go[y] = x ;
		val[y] = max(val[x], z) ;
		dfs(y, x) ;
	}
}

void dfs2(int x, int f)
{
	for(auto [y, z] : g[x]) if(y != f)
	{
		val2[y] = max(val2[x], z) ;
		dfs2(y, x) ;
	}
}

int main()
{
	ios::sync_with_stdio(false) ;
	cin.tie(nullptr) ;
	
	cin >> n >> m ;
	for(int i = 1; i <= m; ++ i)
	{
		cin >> L[i] >> R[i] >> w[i] ;
		id[i] = i ;
	}

	stable_sort(id + 1, id + m + 1, [&](int x, int y) {
		return w[x] < w[y] ;
	}) ;

	if(m == 1) return cout << w[1] << '\n', 0 ;
	
	for(int i = 1; i <= n; ++ i) fa[i] = i ;

	int maxz = 0 ;
	for(int i = 1; i <= m; ++ i)
	{
		int x = L[id[i]], y = R[id[i]], z = w[id[i]] ;

		if(!isMerge(x, y))
		{
			merge(x, y) ;
			in[id[i]] = 1 ;
			g[x].push_back({y, z}) ;
			g[y].push_back({x, z}) ;
			maxz = z ;
		}
 	}

 	dfs(1, 0) ;
 	dfs2(n, 0) ;

 	vector<int> dist ;
 	int pos = n ;
 	while(pos != 1) dist.push_back(pre[pos]), pos = go[pos] ;

 	sort(dist.begin(), dist.end(), greater<int>()) ; 

 	ll ans = INT_MAX ;

 	if((int)dist.size() == 1) ans = dist[0] ;
 	else ans = dist[0] + dist[1] ;

 	// for(int i = 1; i <= m; ++ i) cout << in[id[i]] << " \n"[i == m] ;

 	for(int i = 1; i <= m; ++ i) if(w[id[i]] >= maxz)
 	{
 		// if(in[id[i]]) continue ;
 		// cout << "KK" << '\n' ;
 		int x = L[id[i]], y = R[id[i]], z = w[id[i]] ;
 		ans = min(ans, max(val[x], val2[y]) + (ll)z) ;
 		ans = min(ans, max(val2[x], val[y]) + (ll)z) ;
 	}

 	cout << ans << '\n' ;
	return 0 ;
}