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#include <iostream>
#include <vector>
#include <set>
#include <cstring>
#include <queue>
#include <cmath>
#include <algorithm>
using namespace std;
const int maxn = 1e5 + 10;
int idx[maxn], sz[maxn];
int find_root(int x) {
    while(x != idx[x]) {
        idx[x] = idx[idx[x]];
        x = idx[x];
    }
    return x;
}
bool check(int a, int b) {
    if(find_root(a) == find_root(b)) {
        return true;
    }
    return false;
}
void unite(int a, int b) {
    int a_root = find_root(a);
    int b_root = find_root(b);
    
    if(a_root != b_root) {
        
        if(sz[a_root] < sz[b_root]) {
            idx[a_root] = idx[b_root];
            sz[b_root] += sz[a_root];
        }
        else {
            idx[b_root] = idx[a_root];
            sz[a_root] += sz[b_root];
        }
        
    }
    
}
int main() {
    for(int i = 0; i < maxn; i++) {
        idx[i] = i;
        sz[i] = 1;
    }
    int n, m;
    cin >> n >> m;
    
    vector<pair<int, pair<int, int> > > graph;
    
    for(int i = 0; i < m; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        graph.push_back(make_pair(c, make_pair(a, b)));
    }
    sort(graph.begin(), graph.end());
    int MST = 0;
    
    for(int i = 0; i < m; i++) {
        int a = graph[i].second.first;
        int b = graph[i].second.second;
        int c = graph[i].first;
        
        if(!check(a, b)) {
            MST += c;
            cout << a << " " << b << endl;
            unite(a, b);
        }
        
    }
    cout << MST << endl;
    return 0;
}