// include
//------------------------------------------
#include <bits/stdc++.h>

using namespace std;

// conversion
//------------------------------------------
inline int toInt(string s) {
    int v;
    istringstream sin(s);
    sin >> v;
    return v;
}
template <class T>
inline string toString(T x) {
    ostringstream sout;
    sout << x;
    return sout.str();
}

// math
//-------------------------------------------
template <class T>
inline T sqr(T x) {
    return x * x;
}

// typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

// container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i, c) \
    for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)

// constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF_INT = 2147483647;
const LL INF_LL = 9223372036854775807;

// clear memory
//--------------------------------------------
#define CLR(a) memset((a), 0, sizeof(a))

// vector
//--------------------------------------------
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
    for (T &x : vec) is >> x;
    return is;
}

// pair
//--------------------------------------------
template <typename T, typename U>
ostream &operator<<(ostream &os, pair<T, U> &pair_var) {
    os << "(" << pair_var.first << ", " << pair_var.second << ")";
    return os;
}

// vector
//--------------------------------------------
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec) {
    os << "{";
    for (int i = 0; i < vec.size(); i++) {
        os << vec[i] << (i + 1 == vec.size() ? "" : ", ");
    }
    os << "}";
    return os;
}

// list
//--------------------------------------------
template <typename T>
ostream &operator<<(ostream &os, const list<T> &lst) {
    os << "{";
    REPI(itr, lst) {
        os << *itr;
        itr++;
        if (itr != lst.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// map
//--------------------------------------------
template <typename T, typename U>
ostream &operator<<(ostream &os, map<T, U> &map_var) {
    os << "{";
    REPI(itr, map_var) {
        os << *itr;
        itr++;
        if (itr != map_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// set
//--------------------------------------------
template <typename T>
ostream &operator<<(ostream &os, set<T> &set_var) {
    os << "{";
    REPI(itr, set_var) {
        os << *itr;
        itr++;
        if (itr != set_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// dump
//--------------------------------------------
#define DUMPOUT cerr

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&... tail) {
    DUMPOUT << head;
    if (sizeof...(Tail) > 0) {
        DUMPOUT << ", ";
    }
    dump_func(std::move(tail)...);
}
#ifdef DEBUG_
#define DEB
#define dump(...)                                                       \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                     \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" \
            << endl                                                     \
            << "    ",                                                  \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

class DisjointSet {
public:
    VI rank, p;

    DisjointSet() {}
    DisjointSet(int size) {
        rank.resize(size, 0);
        p.resize(size, 0);
        REP(i, size) p[i] = i;
    }

    void makeSet(int x) {
        p[x] = x;
        rank[x] = 0;
    }

    bool same(int x, int y) { return _findSet(x) == _findSet(y); }

    void unite(int x, int y) { _link(_findSet(x), _findSet(y)); }

private:
    void _link(int x, int y) {
        if (rank[x] > rank[y]) {
            p[y] = x;
        } else {
            p[x] = y;
            if (rank[x] == rank[y]) {
                rank[y]++;
            }
        }
    }

    int _findSet(int x) {
        if (x != p[x]) {
            p[x] = _findSet(p[x]);
        }
        return p[x];
    }
};

class Edge {
public:
    int source, target, cost;
    Edge(int source = 0, int target = 0, int cost = 0)
        : source(source), target(target), cost(cost) {}
    bool operator<(const Edge &e) const { return cost < e.cost; }
};

int kruskal(int N, vector<Edge> edges) {
    int totalCost = 0;
    sort(edges.begin(), edges.end());
    DisjointSet dset = DisjointSet(N + 1);

    REP(i, N) dset.makeSet(i);

    REP(i, edges.size()) {
        Edge e = edges[i];
        if (!dset.same(e.source, e.target)) {
            totalCost += e.cost;
            dset.unite(e.source, e.target);
        }
    }
    return totalCost;
}

int main(void) {
    int N, M;
    cin >> N >> M;
    vector<Edge> edges;
    REP(i, M) {
        int source, target, cost;
        cin >> source >> target >> cost;
        edges.PB(Edge(source, target, cost));
    }
    cout << kruskal(N, edges) << endl;
    return 0;
}



Measured memory_bytes: 5432