#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using vi = vector < int >;
using pii = pair < int, int >;
#define pb push_back
#define sz(x) ((int)(x).size())
#define all(a) (a).begin(), (a).end()
#define qio() cin.tie(0) -> sync_with_stdio(0)
#define L(i, j, k) for (int i = j; i <= int(k); i++)
#define R(i, j, k) for (int i = j; i >= int(k); i--)
 
const int N = 3e5 + 5, V = 602;
 
int n, a[N], Rs, lb[N], rb[N], mat[V];
int fa[V], vs[V], es[V], rt[V];
vi pool;
bool spare[N], match[N];
int even[V][V];
vi odd[V][V];
vi T[V], G[V];
vector < array < int, 3 > > edge;
 
inline int find(int x) {
	return fa[x] == x ? x : fa[x] = find(fa[x]);
}
void merge(int x, int y) {
	if ((x = find(x)) == (y = find(y))) {
		return void(es[x]++);
	}
	if (vs[x] < vs[y]) swap(x, y);
	fa[y] = x, vs[x] += vs[y], es[x] += es[y] + 1;
}
 
namespace Match {
	int dsu[V], pre[V], vis[V];
	inline int find(int x) {
		return x == dsu[x] ? x : dsu[x] = find(dsu[x]);
	}
	void bfs(int s) {
		L(i, 0, V - 1) {
			vis[i] = pre[i] = 0;
			dsu[i] = i;
		}
		queue < int > Q;
		auto lca = [&](int u, int v) {
			static int dfn[N], dfc;
			for (dfc++; ; swap(u, v)) {
				if (dfn[u = find(u)] == dfc) return u;
				if (u) dfn[u] = dfc;
				u = pre[mat[u]];
			}
			return -1;
		};
		auto blossom = [&](int u, int v, int lc) {
			for (; find(u) != lc; u = pre[v]) {
				pre[u] = v, v = mat[u];
				vis[v] = 1, Q.push(v);
				dsu[u] = dsu[v] = lc; // dsu not fa
			}
		};
		for (vis[s] = 1, Q.push(s); sz(Q); Q.pop()) {
			int u = Q.front();
			for (auto v : G[u]) if (find(u) != find(v) && vis[v] != 2) {
				if (vis[v] == 1) {
					int lc = lca(u, v);
					blossom(u, v, lc);
					blossom(v, u, lc);
					continue;
				}
				vis[v] = 2, pre[v] = u;
				if (!mat[v]) {
					for (int o; u; u = pre[v = o]) {
						pre[u] = o = mat[u];
						mat[u] = v, mat[v] = u;
					}
					return;
				}
				vis[mat[v]] = 1, Q.push(mat[v]);
			}
		}
	}
}
 
bool vis[V];
void dfs(int u) {
	vis[u] = 1;
	for (auto v : T[u]) {
		if (!match[v] && sz(odd[u][v])) {
			match[v] = 1;
			int w = odd[u][v].back();
			odd[u][v].pop_back(), odd[v][u].pop_back();
			if (a[lb[w]] == v) a[lb[w] + 1] = v;
			else a[rb[w] - 1] = v;
			dfs(v);
		} else if (!vis[v]) dfs(v);
	}
}
 
int main() {
	qio(), cin >> n;
	memset(spare, 1, sizeof spare);
	a[0] = a[n + 1] = N - 1, match[a[0]] = 1;
	L(i, 1, n) cin >> a[i];
	L(i, 1, n) {
		if (a[i] == a[i - 1]) {
			spare[a[i]] = 0;
			match[a[i]] = 1;
		} 
		if (!a[i - 1] || !a[i + 1]) spare[a[i]] = 0; // - 1 忘记打了呃呃
	}
	L(i, 1, n) if (spare[i]) {
		pool.pb(i);
	}
	iota(fa, fa + V, 0);
	fill(vs, vs + V, 1);
	for (int las = 0, i = 1; i <= n + 1; i++) {
		if (a[i]) {
			int len = i - las - 1;
			bool lhs = !match[a[las]], rhs = !match[a[i]];
			if (len) lb[++Rs] = las, rb[Rs] = i;
			if (len & 1) {
				if (lhs && rhs && a[las] != a[i]) {
					T[a[las]].pb(a[i]);
					T[a[i]].pb(a[las]);
					odd[a[i]][a[las]].pb(Rs);
					odd[a[las]][a[i]].pb(Rs);
					merge(a[i], a[las]);
//					cerr << las << ' ' << i << " qwq\n";
				} else if (lhs) {
					match[a[las]] = 1;
					a[las + 1] = a[las];
				} else if (rhs) {
					match[a[i]] = 1;
					a[i - 1] = a[i];
				}
			} else if (len && lhs && rhs && a[i] != a[las]) {
//				cerr << las << ' ' << i << " qaq\n";
				edge.pb({a[i], a[las], Rs});
			}
			las = i;
		}
	}
	for (auto [u, v, w] : edge) if (!match[u] && !match[v]) {
//		cerr << "try " << u << ' ' << v << '\n';
		if ((u = find(u)) != (v = find(v)) && vs[u] == es[u] + 1 && vs[v] == es[v] + 1) {
//			cerr << "    " << u << " - " << v << '\n';
			even[u][v] = even[v][u] = w;
			G[u].pb(v), G[v].pb(u);
		}
	}
	L(i, 1, V - 2) if (!mat[i]) { // 没有匹配才可以跑
		Match::bfs(i);
	}
	L(i, 1, V - 2) rt[find(i)] = find(i);
	L(i, 1, V - 2) if (mat[i]) {
		int w = even[i][mat[i]], x = a[lb[w]], y = a[rb[w]];
//		cerr << "match " << x << ' ' << y << "; " << lb[w] << ' ' << rb[w] << '\n';
		match[x] = match[y] = 1;
		rt[i] = find(x) == i ? x : y;
		a[lb[w] + 1] = x;
		a[rb[w] - 1] = y;
	}
	L(i, 1, V - 2) if (fa[i] == i) {
		dfs(rt[i]);
	}
	L(i, 1, n) {
		if (!a[i]) {
			if (!a[i + 1] && sz(pool)) {
				a[i] = a[i + 1] = pool.back();
				pool.pop_back();
			} else a[i] = 1; // a[i + 1] should not be changed
		}
		cout << a[i] << " \n"[i == n];
	}
	return 0;
}