#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define op(x) ((x&1)?x+1:x-1)
#define odd(x) (x&1)
#define even(x) (!odd(x))
#define lc(x) (x<<1)
#define rc(x) (lc(x)|1)
#define lowbit(x) (x&-x)
#define mp(x,y) make_pair(x,y)
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
using namespace std;
const int MAXN = 3e5+10,MAXM = 1e6+10,INF = 2e9+10;
typedef array<int,2> pr;
typedef array<int,3> tr;
void tomin(int& x,int y){x=min(x,y);}
int n,m,ans=INF;
tr e[MAXM];
vector<pr>t[MAXN];
int fa[MAXM],f[MAXN],g[MAXN],suf[MAXM],tag[MAXM];

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

void dfs(int u,int fa,int* f,int val){
	f[u]=val;
	for(auto [v,w]:t[u])if(v^fa){
		dfs(v,u,f,max(val,w));
	}
}

int main(){
	ios::sync_with_stdio(false);cin.tie(0);

	cin>>n>>m;
	rep(i,1,m)cin>>e[i][1]>>e[i][2]>>e[i][0];
	sort(e+1,e+1+m);
	rep(i,1,n)fa[i]=i;

	rep(i,1,m){
		int u=e[i][1],v=e[i][2];
		if(u>v)swap(u,v);
		if(u==1 && v==n){
			tomin(ans,e[i][0]);
		}
		if(find(u) != find(v)){
			fa[find(u)] = find(v);
			t[u].push_back({v,i});
			t[v].push_back({u,i});
		}
	}

	dfs(1,0,f,0);
	dfs(n,0,g,0);

	iota(fa+1,fa+m+2,1);

	rep(i,1,m)suf[i]=INF;
	rep(i,1,m){
		int u=e[i][1],v=e[i][2];
		int L=min(max(f[u],g[v]),max(f[v],g[u]));
		int R=min(max(f[u],f[v]),max(g[u],g[v]));
		for(int pos=find(L);pos<R;pos=find(pos)){
			fa[pos]=pos+1;
			suf[pos]=e[i][0];
		}
	}	
	rep(i,1,m){
		tomin(ans,e[i][0] + suf[i]);
	}

	assert(ans^INF);
	cout<<ans<<endl;
    return 0;
}