#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T &x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N = 3e5 + 7;

int fa[N];
vector<int> ele[N];
int mx1[N];
int mxn[N];

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

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int n, m; r(n), r(m);
    vector<pair<int, pair<int, int>>> edges;
    for(int i = 1; i <= m; ++i){
        int u, v, w; r(u), r(v), r(w);
        edges.push_back({w, {u, v}});
    }
    sort(edges.begin(), edges.end());
    for(int i = 1; i <= n; ++i){
        fa[i] = i;
        ele[i].push_back(i);
    }
    for(auto &e : edges){
        int w = e.first;
        int u = e.second.first;
        int v = e.second.second;
        u = find(u);
        v = find(v);
        if(u == v) continue;

        if(u == find(1)) for(auto &x: ele[v]) mx1[x] = w;
        if(v == find(1)) for(auto &x: ele[u]) mx1[x] = w;
        if(u == find(n)) for(auto &x: ele[v]) mxn[x] = w;
        if(v == find(n)) for(auto &x: ele[u]) mxn[x] = w;

        if(ele[u].size() < ele[v].size()) swap(u, v);
        // ele[u].insert(ele[u].end(), ele[v].begin(), ele[v].end());
        for(auto &x: ele[v]) ele[u].push_back(x);
        ele[v].clear();
        fa[v] = u;
    }
    int ans = 2e9;
    for(auto &e : edges){
        int w = e.first;
        int u = e.second.first;
        int v = e.second.second;
        if(abs(u - v) == n - 1){
            ans = min(ans, w);
        }
        else{
            if(mx1[u] <= w && mxn[v] <= w){
                ans = min(ans, w + max(mx1[u], mxn[v]));
            }
            if(mx1[v] <= w && mxn[v] <= w){
                ans = min(ans, w + max(mx1[v], mxn[u]));
            }
        }
        
    }
    printf("%d\n", ans);
    return 0;
}