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

struct Edge{
	int x,y,val;
}ed[1000010];
int n,m;
int ans;
int fa[300010];

void init()
{
	for(int i=1;i<=n;i++) fa[i]=i;
}

int Find(int x)
{
	if(fa[x]==x) return x;
	return fa[x]=Find(fa[x]);
}

void Merge(int x,int y)
{
	x=Find(x);
	y=Find(y);
	if(x!=y) fa[x]=y;
}

bool cmp(Edge x,Edge y)
{
	return x.val<y.val;
}

int check(int mid)
{
	init();
	Merge(ed[mid].x, ed[mid].y);
	if(Find(1)==Find(n)) return 0;
	for(int i=1;i<mid;i++)
	{
		Merge(ed[i].x, ed[i].y);
		if(Find(1)==Find(n)) return i;
	}
	return -1;
}

int si[300010];
vector<pair<int,int> > vec;

int find(int x)
{
	if(fa[x]==x) return x;
	return find(fa[x]);
}

void merge(int x,int y)
{
	x=find(x);
	y=find(y);
	if(si[x]>si[y]) swap(x, y);
	vec.push_back(make_pair(x, fa[x]));
	if(x==y) return ;
	fa[x]=y;
	si[y]+=si[x];
}

void del()
{
	auto tem=vec.back();
	int x=tem.first;
	int y=tem.second;
	vec.pop_back();
	if(y==fa[x]) return ;
	fa[x]=x;
	si[y]-=si[x];
}

bool doit(int x,int y,int mid)
{
	int xx=find(ed[mid].x);
	int yy=find(ed[mid].y);
	if((xx==x&&yy==y)||(xx==y&&yy==x)) return 1;
	return 0;
}

int main(){
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(false);
	cin>>n>>m;
	for(int i=1;i<=m;i++) cin>>ed[i].x>>ed[i].y>>ed[i].val;
	sort(ed+1,ed+1+m,cmp);
	int l=1,r=m,nr,nl;
	while(l<=r)
	{
		int mid=(l+r)>>1;
		int tem=check(mid);
		if(tem!=-1)
		{
			nl=tem;
			nr=mid;
			r=mid-1;
		}
		else l=mid+1;
	}
	init();
	for(int i=1;i<=nl;i++)
	{
		merge(ed[i].x, ed[i].y);
	}
	ans=ed[nr].val+ed[nl].val;
	while(nl)
	{
		del();
		nl--;
		int x=find(1);
		int y=find(n);
		while(nr<m&&!doit(1, n, nr))
		{
			if(ed[nl-1].val+ed[nr].val>ans) break;
			nr++;
		}
		if(nr>m) break;
		ans=min(ans,ed[nl].val+ed[nr].val);
	}
	cout<<ans;
	return 0;
}