#include <bits/stdc++.h>
 
using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;
 
#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
 
template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) { 
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
    out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
    out<<'['; for(T i: a) {out<<i<<',';} out<<']'; return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

struct UnionFind {
    vector<int> par, s;
    UnionFind(int n=2e5) { init(n); }
    void init(int n) {
        s.assign(n, 1); par.resize(n);
        iota(par.begin(), par.end(), 0);
    }
    int find(int x) {
        if(par[x] == x) return x;
        return par[x] = find(par[x]);
    }
    void unite(int x, int y) {
        x = find(x);
        y = find(y);
        if(x == y) return;
        if(s[x] < s[y]) par[x] = y, s[y] = s[x] + s[y];
        else par[y] = x, s[x] = s[x] + s[y];
    }
    bool same(int x, int y) { return find(x) == find(y); }
    int size(int x) { return s[find(x)]; }
};

template<typename T, typename F>
T boruvka(ll n, F f) {
    vector<ll> rev(n), belong(n);
    UnionFind uf(n);
    T ret = 0;
    while(uf.size(0) != n) {
        ll ptr = 0;
        rev.assign(n, -1);
        REP(i, n) if(uf.find(i) == i) belong[i] = ptr++;
        REP(i, n) belong[i] = belong[uf.find(i)], rev[belong[i]] = i;
        vector<PII> v = f(ptr, belong);
        bool update = false;
        REP(i, ptr) {
            if(~v[i].second && !uf.same(rev[i], rev[v[i].second])) {
                uf.unite(rev[i], rev[v[i].second]);
                ret += v[i].first;
                update = true;
            }
        }
        if(!update) {
            // cerr << belong << endl;
            // cerr << "sz=" << ptr << endl;
            return -1; // notice!!
        }
    }
    return ret;
}

signed main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll n, m;
    cin >> n >> m;
    vector<vector<PII>> g(n);
    REP(i, m) {
        ll a, b, c;
        cin >> a >> b >> c;
        g[a].push_back({b, c});
        g[b].push_back({a, c});
    }

    // O(fの計算量 * logV)
    // 各頂点から最小のコストの辺を求める
    // sz=連結成分数 belong[i]=i番目の頂点が属する連結成分
    function<vector<PII>(ll,vector<ll>)> f = [&](ll sz, vector<ll> belong) {
        // ret[i] = (連結成分iからコスト最小の辺の(コスト, i以外の端点の連結成分))
        // iがufの親以外ならsecondは-1として連結成分ごとに管理
        vector<PII> ret(sz, PII(LLINF, -1));

        REP(i, n) for(auto to: g[i]) {
            if(belong[i] == belong[to.first]) continue;
            chmin(ret[belong[i]], PII(to.second, belong[to.first]));
        }
        return ret;
    };
    cout << boruvka<ll, decltype(f)>(n, f) << endl;

    return 0;
}



Measured memory_bytes: 8860