#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<int> G[N<<2];
int w[N<<2], f[N<<2], dep[N<<2], mxd[N<<2], ch[N<<2], par[N<<2];

void add_edge(int u, int v) {
    G[u].emplace_back(v);
    G[v].emplace_back(u);
}
void dfs(int u, int fa, int d) {
    f[u] = fa;
    dep[u] = d;
    mxd[u] = d;
    ch[u] = 0;
    for (auto& v : G[u]) {
        if (v == fa) continue;
        dfs(v, u, d+1);
        if (mxd[v] > mxd[u]) {
            mxd[u] = mxd[v];
            ch[u] = v;
        }
    }
}
void dfs1(int u, int fa, int p) {
    par[u] = p;
    for (auto& v : G[u]) {
        if (v == fa) continue;
        if (v == ch[u]) dfs1(v, u, p);
        else dfs1(v, u, v);
    }
}
int lca(int u, int v) {
    while (par[u] != par[v]) {
        if (dep[u] > dep[v]) {
            u = f[par[u]];
        } else {
            v = f[par[v]];
        }
    }
    return dep[u] < dep[v] ? u : v;
}

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;
    w[++ z] = l;
    add_edge(z, rt[u]), add_edge(z, rt[v]);
    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(edgs.begin(), edgs.end());
    for (int i = 0; i < m; ++ i) {
        auto& [l, u, v] = edgs[i];
        join(u, v, l);
        flg[i] = find(1) == find(n);
    }
    dfs(z, z, 0);
    dfs1(z, z, z);

    for (int i = 0; i < m; ++ i) {
        if (!flg[i]) continue;
        auto& [l, u, v] = edgs[i];
        res = min(res, l + max(w[lca(u, 1)], w[lca(v, n)]));
        res = min(res, l + max(w[lca(u, n)], w[lca(v, 1)]));
    }

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