#include <cstdio>
#include <queue>
#include <utility>
#define rep(i, d, u) for(int i = d; i <= u; ++i)
int ured() {
	int ch, re = 0;
	do {
		ch = getchar();
	} while(ch < '0' || '9' < ch);
	do {
		re = re * 10 + (ch ^ '0');
	} while('0' <= (ch = getchar()) && ch <= '9');
	return re;
}
void uwit(int da) {
	int ch[21], cn = 0;
	do {
		ch[++cn] = da % 10;
	} while(da /= 10);
	do {
		putchar('0' ^ ch[cn]);
	} while(--cn);
}
const int _maxn = 200011;
int n, m, x[_maxn], lasp[_maxn], rans[_maxn], tpos;
std :: priority_queue<std :: pair<int, int>> lasq;
std :: priority_queue<int> datq;
bool firp[_maxn], used[_maxn];
int main() {
	n = ured(), m = ured();
	rep(i, 1, n) {
		x[i] = ured();
		if(!lasp[x[i]]) {
			firp[i] = 1;
		}
		lasp[x[i]] = i;
	}
	rep(i, 1, m) {
		lasq . push(std :: make_pair(-lasp[i], i));
	}
	rep(i, 1, m) {
		while(used[lasq . top() . second]) {
			lasq . pop();
		}
		while(tpos < -lasq . top() . first) {
			if(firp[++tpos]) {
				datq . push(-x[tpos]);
			}
		}
		used[rans[i] = -datq . top()] = 1, datq . pop();
	}
	rep(i, 1, m) {
		uwit(rans[i]), putchar(i == m ? '\n' : ' ');
	}
	return 0;
}