#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define PII pair<int,int>
#define fi first
#define se second
#define sz(x) (int)(x.size())
#define all(x) x.begin(),x.end()
#define Nai_Long return 0
#define See_Memory cerr<<abs(&M1-&M2)/1024.0/1024.0<<"MB\n"
#define See_Time cerr<<(clock()-T)*1.0/CLOCKS_PER_SEC<<"s\n"
using namespace std;
const int N=1e6+10,M=1e6+10,MOD=998244353;
bool M1;
mt19937 rng(time(0));
namespace MTool
{
	inline int Cadd(int a,int b){return a+b>=MOD?a+b-MOD:a+b;}
	inline int Cdel(int a,int b){return a-b<0?a-b+MOD:a-b;}
	inline int Cmul(int a,int b){return 1ll*a*b%MOD;}
	inline void Madd(int &a,int b){a=(a+b>=MOD?a+b-MOD:a+b);}
	inline void Mdel(int &a,int b){a=(a-b<0?a-b+MOD:a-b);}
	inline void Mmul(int &a,int b){a=1ll*a*b%MOD;}
	inline int Cmod(int x){return (x%MOD+MOD)%MOD;}
	inline void Mmod(int &x){x=(x%MOD+MOD)%MOD;}
	template<typename T> inline bool Mmax(T&a,T b){return a<b?a=b,1:0;}
	template<typename T> inline bool Mmin(T&a,T b){return a>b?a=b,1:0;}
	template<typename...Args> inline int Cadd(int a,int b,Args...args){return Cadd(Cadd(a,b),args...);}
	template<typename...Args> inline int Cmul(int a,int b,Args...args){return Cmul(Cmul(a,b),args...);}
	template<typename...Args> inline int Cdel(int a,int b,Args...args){return Cdel(Cdel(a,b),args...);}
	template<typename...Args> inline void Madd(int &a,int b,Args...args){Madd(a,b),Madd(a,args...);}
	template<typename...Args> inline void Mdel(int &a,int b,Args...args){Mdel(a,b),Mdel(a,args...);}
	template<typename...Args> inline void Mmul(int &a,int b,Args...args){Mmul(a,b),Mmul(a,args...);}
	template<typename...Args,typename T> inline bool Mmax(T&a,T b,Args...args){return Mmax(a,b)|Mmax(a,args...);}
	template<typename...Args,typename T> inline bool Mmin(T&a,T b,Args...args){return Mmin(a,b)|Mmin(a,args...);}
	int ksm(int x,int y){int s=1;for(;y;y>>=1,Mmul(x,x)) if(y&1) Mmul(s,x); return s;}
}
using namespace MTool;
int n,m; 
struct Edge
{
	int u,v,w; 
	friend bool operator <(Edge x,Edge y)
	{
		return x.w<y.w;
	}
}E[M];
struct DSU
{
	int f[N];
	void Init()
	{
		for(int i=1;i<=n+n;++i) f[i]=i;
	}
	int Find(int x)
	{
		if(f[x]==x) return f[x];
		return f[x]=Find(f[x]);
	}
	int Check(int x,int y)
	{
		return Find(x)==Find(y);
	}
	void Merge(int x,int y)
	{
		x=Find(x),y=Find(y);
		f[x]=y;
	}
}D;
vector<PII> g[N]; int cnt=0; 
void Kruskal()
{
	sort(E+1,E+m+1); D.Init(); 
	for(int i=1;i<=m;++i)
	{
		int u=E[i].u,v=E[i].v,w=E[i].w;
		if(D.Check(u,v)) continue;
		g[u].push_back({v,w});
		g[v].push_back({u,w});
		D.Merge(u,v); cnt++;
		if(cnt==n-1) break;
	}
}
int dis1[N],dis2[N];
void Dfs1(int u,int fa)
{
	for(PII k:g[u]) 
	{
		if(k.fi==fa) continue;
		dis1[k.fi]=max(dis1[u],k.se); 
		Dfs1(k.fi,u); 
	}
}
void Dfs2(int u,int fa)
{
	for(PII k:g[u]) 
	{
		if(k.fi==fa) continue;
		dis2[k.fi]=max(dis2[u],k.se); 
		Dfs2(k.fi,u); 
	}
}
void Solve()
{
	cin>>n>>m; int ans=2e9;
	for(int i=1;i<=m;++i)
	{
		int u,v,w; cin>>u>>v>>w;
		E[i]={u,v,w};
		if(u==1&&v==n) Mmin(ans,w);
		if(u==n&&v==1) Mmin(ans,w);
	}
	Kruskal(); Dfs1(1,0); Dfs2(n,0);
	for(int i=1;i<=m;++i)
	{
		int u=E[i].u,v=E[i].v,w=E[i].w;
		if(dis1[u]<=w&&dis2[v]<=E[i].w) Mmin(ans,max(dis1[u],dis2[v])+w);
		if(dis1[v]<=w&&dis2[u]<=E[i].w) Mmin(ans,max(dis1[v],dis2[u])+w);
	}
	cout<<ans<<'\n';
}
bool M2;
int main()
{
//	freopen("takeout.in","r",stdin);
//	freopen("takeout.out","w",stdout);
	ios::sync_with_stdio(false); cin.tie(nullptr);
	int T=clock();
	int t=1; //cin>>t;
	while(t--) Solve();
	See_Memory; See_Time;
	Nai_Long;
}