#include <bits/stdc++.h>
using namespace std;
const long long MAX = 1000000000;
const int N = 100005;
struct Edge {
  int to, next, w, vis;
};
struct Edge e[N << 1];
int head[N], E, f[N];
struct P {
  long long val;
  int idx;
  P(long long val, int idx) : val(val), idx(idx) {}
  bool operator<(const P &h) const { return val > h.val; }
};
priority_queue<P> Q;
long long dfs(int u) {
  f[u] = 1;
  long long ret = 0;
  for (int i = head[u]; i != -1; i = e[i].next) {
    if (e[i].vis) continue;
    e[i].vis = e[i ^ 1].vis = 1;
    ret += e[i].w;
    if (!f[e[i].to]) ret += dfs(e[i].to);
  }
  return ret;
}
void addedge(int u, int to, int w) {
  e[E].to = to;
  e[E].w = w;
  e[E].vis = 0;
  e[E].next = head[u];
  head[u] = E++;
}
int main() {
  memset(head, -1, sizeof head);
  E = 0;
  int n, m, p, q;
  scanf("%d%d%d%d", &n, &m, &p, &q);
  int uu, vv;
  for (int i = 0; i < m; i++) {
    int u, v, w;
    scanf("%d%d%d", &u, &v, &w);
    addedge(u, v, w);
    addedge(v, u, w);
    uu = u, vv = v;
  }
  int tot = 0;
  for (int i = 1; i <= n; i++) {
    if (!f[i]) {
      long long val = dfs(i);
      Q.push(P(val, i));
      tot++;
    }
  }
  if (p + q < tot || tot < q) {
    puts("NO");
    return 0;
  }
  if (m == 0) {
    if (p > 0 && q == n) {
      puts("NO");
      return 0;
    }
  }
  puts("YES");
  tot -= q;
  int sum = 0;
  while (sum < tot) {
    P c1 = Q.top();
    Q.pop();
    P c2 = Q.top();
    Q.pop();
    printf("%d %d\n", c1.idx, c2.idx);
    uu = c1.idx, vv = c2.idx;
    long long add = min(MAX, c1.val + c2.val + 1);
    c1.val += add + c2.val;
    Q.push(c1);
    sum++;
  }
  for (int i = 0; i < p - tot; i++) {
    printf("%d %d\n", uu, vv);
  }
  return 0;
}
