#include<bits/stdc++.h>
using namespace std;
const int N = 600005;
#define mp make_pair
#define pb push_back

int n,m;
vector< int >G[N];

struct edge{
	int u,v;
	long long w;
	bool operator <(const edge &o)const{
		return w<o.w;
	}
}e[2000005];

long long p[N];

int f[N];
int g[N][20];

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

int dep[N];

void dfs(int u){
	for(auto v:G[u]){
		dep[v]=dep[u]+1;
		dfs(v);
	}
}

int LCA(int x,int y){
	if(x==y)return x;
	if(dep[x]<dep[y])swap(x,y);
	for(int i=19;i>=0;i--)if(dep[g[x][i]]>=dep[y])x=g[x][i];
	if(x==y)return x;
	for(int i=19;i>=0;i--)if(g[x][i]!=g[y][i])x=g[x][i]; // fa[x][20]=fa[y][20]=0
	return g[x][0];
}

int main(){
	cin>>n>>m;
	for(int i=1;i<=m;i++){
		int u,v;
		long long w;
		cin>>u>>v>>w;
		e[i]=(edge){u,v,w};
	}
	sort(e+1, e+1+m);

	for(int i=1;i<=n+n-1;i++){
		f[i]=i;
	}

	int tot=n;
	for(int i=1;i<=m;i++){
		if(find(e[i].u)!=find(e[i].v)){
			++tot;
			g[find(e[i].u)][0]=tot;
			G[tot].push_back(find(e[i].u));
			G[tot].push_back(find(e[i].v));
			// printf("%d -> %d\n",find(e[i].u), tot);
			// printf("%d -> %d\n",find(e[i].v), tot);
			g[find(e[i].v)][0]=tot;
			f[find(e[i].u)]=tot;
			f[find(e[i].v)]=tot;
			p[tot]=e[i].w;
		}
	}
	
	for(int j=1;j<20;j++){
		for(int i=1;i<=tot;i++){
			g[i][j]=g[g[i][j-1]][j-1];
		}
	}

	dep[tot]=1;
	dfs(tot);

	long long ans = 2000000005;

	for(int i=1;i<=m;i++){
		// printf("(%d, %d) w = %lld, LCA(1,%d)=%d, LCA(n,%d)=%d\n",e[i].u,e[i].v,e[i].w,e[i].u,LCA(1,e[i].u),e[i].v,LCA(n,e[i].v));
		// printf(" 1: %lld, 2: %lld\n",max(p[LCA(1,e[i].v)], p[LCA(n,e[i].u)]) , max(p[LCA(1,e[i].u)], p[LCA(n,e[i].v)]));
		long long t1 = max(p[LCA(1,e[i].v)], p[LCA(n,e[i].u)]);
		long long t2 = max(p[LCA(1,e[i].u)], p[LCA(n,e[i].v)]);
		if(e[i].w>=min(t1,t2))
			ans = min(ans,e[i].w+ min( t1,t2 ));
		// printf("ans = %lld\n",ans);
	}

	cout<<ans;

	return 0;

}