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

#define ll long long 
#define lll __int128
#define INF 0x3f3f3f3f
#define LNF 0x3f3f3f3f3f3f3f3fll
#define MOD 998244353
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ld long double
#define fi first
#define se second
#define all(a) a.begin(), a.end()

#define N 300010
#define K 22

vector<pii> G[N];
int w1[N], w2[N];

void add_edge(int u, int v, int l) {
    G[u].emplace_back(v, l);
    G[v].emplace_back(u, l);
}
void dfs1(int u, int fa, int w) {
    w1[u] = w;
    for (auto [v, l] : G[u]) {
        if (v == fa) continue;
        dfs1(v, u, max(w, l));
    }
}
void dfs2(int u, int fa, int w) {
    w2[u] = w;
    for (auto [v, l] : G[u]) {
        if (v == fa) continue;
        dfs2(v, u, max(w, l));
    }
}

int p[N], rt[N], z, flg[N];

void init(int n) {
    for (int i = 1; i <= n; ++ i) p[i] = rt[i] = i;
    z = n;
}
int find(int x) {
    return p[x] == x ? x : (p[x] = find(p[x]));
}
void join(int u, int v, int l) {
    u = find(u), v = find(v);
    if (u == v) return;
    add_edge(u, v, l);
    p[u] = v;
    rt[v] = z;
}

int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n, m; cin >> n >> m;
    init(n);
    vector<tuple<int, int, int>> edgs;
    for (int i = 0; i < m; ++ i) {
        int u, v, l; cin >> u >> v >> l;
        edgs.emplace_back(l, u, v);
    }
    int res = INF;
    sort(all(edgs)), reverse(all(edgs));
    for (auto [l, u, v] : edgs) join(u, v, l);
    for (int i = 1; i <= n; ++ i) w1[i] = w2[i] = -1;
    dfs1(1, 1, 0);
    dfs2(n, n, 0);
    for (auto [l, u, v] : edgs) {
        if (w1[u] != -1 && w2[v] != -1 && min(w1[u], w2[v]) <= l) {
            res = min(res, l + max(w1[u], w2[v]));
        }
        if (w2[u] != -1 && w1[v] != -1 && min(w2[u], w1[v]) <= l) {
            res = min(res, l + max(w2[u], w1[v]));
        }
    }

    cout << res << '\n';
}