#include <cstdio>
#include <vector>
#include <algorithm>
 
using namespace std;
 
struct Edge {
    int s, e, cost;
 
    Edge(int s, int e, int cost) : s(s), e(e), cost(cost) { }
 
    bool operator < (const Edge &x) const {
        return cost < x.cost;
    }
};
 
int N, M;
 
vector<Edge> edges;
 
int parent[50003];
 
int get_parent(int x) {
    if (x == parent[x]) {
        return x;
    }
    parent[x] = get_parent(parent[x]);
    return parent[x];
}
 
void kruskal() {
    sort(edges.begin(), edges.end());
 
    for (int i = 1; i <= N; i ++) {
        parent[i] = i;
    }
 
    int res = 0;
    for (int i = 0; i < M; i ++) {
        int pa = get_parent(edges[i].s);
        int pb = get_parent(edges[i].e);
        if (pa == pb) {
            continue;
        }
        res += edges[i].cost;
        parent[pa] = pb;
    }
 
    printf("%d\n", res);
}
 
int main() {
    scanf("%d", &N);
    scanf("%d", &M);
 
    for (int i = 0; i < M; i ++) {
        int s, e, c;
        scanf("%d %d %d", &s, &e, &c);
        edges.push_back(Edge(s, e, c));
    }
 
    kruskal();
 
    return 0;
}

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