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Cod sursa(job #870013)
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
#define maxN 200010
#define PB push_back
#define MKP make_pair
#define f first
#define s second
int tata[maxN], sol;
vector < pair <int, pair <int, int> > > edges;
vector < pair <int, int> > ans;
inline int root (int X)
{
int R = X;
for (R = X; R != tata[R]; R = tata[R]);
for (int y; X != R; y = X, X = tata[X], tata[y] = R);
return R;
}
void unite (int x, int y)
{
int rx = root(x), ry = root (y);
tata[rx] = ry;
}
int main()
{
freopen ("apm.in", "r", stdin);
freopen ("apm.out", "w", stdout);
int N, M;
scanf ("%d %d", &N, &M);
while (M --)
{
int x, y, c;
scanf ("%d %d %d", &x, &y, &c);
edges.PB ( MKP (c, MKP (x, y)) );
}
sort (edges.begin(), edges.end());
for (int i = 1; i <= N; ++ i) tata[i] = i;
for (int i = 0; i < edges.size(); ++ i)
{
int x = edges[i].s.f, y = edges[i].s.s;
if (root (x) == root (y)) continue;
unite (x, y);
sol += edges[i].f;
ans.PB ( MKP (x, y) );
}
printf ("%d\n%d\n", sol, ans.size());
for (int i = 0; i < ans.size(); ++ i) printf ("%d %d\n", ans[i].f, ans[i].s);
return 0;
}