You are given a tree (a graph with n vertices and n - 1 edges in which it's possible to reach any vertex from any other vertex using only its edges).

A vertex can be destroyed if this vertex has even degree. If you destroy a vertex, all edges connected to it are also deleted.

Destroy all vertices in the given tree or determine that it is impossible.

Input

The first line contains integer n (1 ≤ n ≤ 2·105) — number of vertices in a tree.

The second line contains n integers p1, p2, ..., pn (0 ≤ pi ≤ n). If pi ≠ 0 there is an edge between vertices i and pi. It is guaranteed that the given graph is a tree.

Output

If it's possible to destroy all vertices, print "YES" (without quotes), otherwise print "NO" (without quotes).

If it's possible to destroy all vertices, in the next n lines print the indices of the vertices in order you destroy them. If there are multiple correct answers, print any.

Examples

Input

5
0 1 2 1 2


Output

YES
1
2
3
5
4


Input

4
0 1 2 3


Output

NO

Note

In the first example at first you have to remove the vertex with index 1 (after that, the edges (1, 2) and (1, 4) are removed), then the vertex with index 2 (and edges (2, 3) and (2, 5) are removed). After that there are no edges in the tree, so you can remove remaining vertices in any order.

<image>
#include <bits/stdc++.h>
using namespace std;
const int N = (int)2e5 + 7;
int n;
vector<int> g[N];
bool deg[N], dp[N], mark[N];
vector<int> result;
void dfs_pre(int v, int p) {
  dp[v] = (deg[v] % 2 == 0);
  for (auto u : g[v]) {
    if (u == p) continue;
    dfs_pre(u, v);
    dp[v] ^= dp[u];
  }
}
void solve(int v) {
  mark[v] = true;
  for (auto u : g[v]) {
    if (mark[u]) continue;
    if (dp[u] == 1) {
      solve(u);
    }
  }
  result.push_back(v + 1);
  for (auto u : g[v]) {
    if (mark[u]) continue;
    solve(u);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr), cout.tie(nullptr);
  int root = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    x--;
    if (x == -1) {
      root = i;
      continue;
    }
    g[x].push_back(i), g[i].push_back(x);
    deg[x] ^= 1, deg[i] ^= 1;
  }
  if (n % 2 == 0)
    return cout << "NO" << endl, 0;
  else
    cout << "YES" << endl;
  dfs_pre(root, root);
  solve(root);
  for (auto v : result) cout << v << endl;
  return 0;
}
