#include <bits/stdc++.h>
#define rep(i,l,r) for(int i=l; i<=r; i++)
#define per(i,r,l) for(int i=r; i>=l; i--)
#define IOS {cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);}
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

const int N = 300030;

struct node {
    int u, v, w;
} e[1000010];
vector <P> ed[N];
int fa[N], to[N], root, b1[N], bn[N], vis1[N], visn[N];
int find(int x) {
    if (x != fa[x]) {
        int t = fa[x];
        fa[x] = find(fa[x]);
        to[x] = max(to[x], to[t]);
    }
    return fa[x];
}

bool cmp(node a, node b) {
    return a.w < b.w;
}

void dfs(int u, int vis[], int b[], int d) {
    vis[u] = 1;
    b[u] = d;
    for (auto [v, w]: ed[u]) {
        if (!vis[v]) {
            dfs(v, vis, b, max(d, w));
        }
    }
}

int main() {
    int n, m; scanf("%d%d", &n, &m);
    rep (i, 1, m) {
        scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);
    }
    sort(e+1, e+m+1, cmp);
    int ans = 2e9;
    rep (i, 1, n) fa[i] = i, b1[i] = 1e9, bn[i] = 1e9;
    b1[1] = 0, bn[n] = 0, vis1[1] = 1, visn[n] = 1;

    rep (i, 1, m) {
        auto [u,v,w] = e[i];
        if (u == 1 && v == n || u == n && v == 1) ans = min(ans, w);
        ans = min(ans, w + max(b1[u], bn[v]));
        ans = min(ans, w + max(bn[u], b1[v]));
        int x = find(u), y = find(v);
        if (x != y) {
            fa[x] = y;
            if (vis1[u]) dfs(v, vis1, b1, max(b1[u], w));
            if (visn[u]) dfs(v, visn, bn, max(bn[u], w));
            if (vis1[v]) dfs(u, vis1, b1, max(b1[v], w));
            if (visn[v]) dfs(u, visn, bn, max(bn[v], w));
            ed[u].push_back(P(v, w));
            ed[v].push_back(P(u, w));
        }
    }
    cout << ans;
    return 0;
}
/*
 4 6
 1 2 2
 1 3 4
 1 4 7
 2 3 1
 2 4 3
 3 4 9
*/