#include <bits/stdc++.h>
using namespace std;
inline int in() {
  int x;
  scanf("%d", &x);
  return x;
}
bool Check(int N, int pos) { return (bool)(N & (1 << pos)); }
int Set(int N, int pos) { return N = N | (1 << pos); }
int fx[] = {+0, +0, +1, -1, -1, +1, -1, +1};
int fy[] = {-1, +1, +0, +0, +1, +1, -1, -1};
int hr[] = {-2, -2, -1, +1, +2, +2, -1, +1};
int hc[] = {+1, -1, +2, +2, -1, +1, -2, -2};
int dx[] = {+1, -1, +0, +0};
int dy[] = {+0, +0, +1, -1};
const int MAXN = (int)1e5 + 9;
int main() {
  long long i, j, k, l, m, n, p, q, x, y, u, v, r, tc, t;
  cin >> n >> k;
  deque<long long> dq;
  map<long long, long long> mp;
  long long cnt = 0;
  for (int i = 1; i <= (int)n; i++) {
    cin >> v;
    if (mp[v] == 1)
      continue;
    else {
      if (cnt < k) {
        dq.push_front(v);
        mp[v] = 1;
        cnt++;
      } else {
        u = dq.back();
        mp[u] = 0;
        cnt--;
        dq.pop_back();
        dq.push_front(v);
        mp[v] = 1;
        cnt++;
      }
    }
  }
  cout << dq.size() << endl;
  for (i = 0; i < dq.size(); i++) cout << dq[i] << " ";
  cout << endl;
  return 0;
}
