#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

const int N = 100010;

int n,root;
bool flag;
int ans;
vector<int> v[N],p;

void dfs(int u)
{
    if(ans != v[u].size() && v[u].size())
    {
        //cout << u << " " << v[u].size() << endl;
        flag = true;
    }
    ans = max(ans,(int)v[u].size());
    p.push_back(u);
    for(int i = 0;i < v[u].size();i ++ )
    {
        dfs(v[u][i]);
    }

}

int main()
{
    cin >> n;
    for(int i = 1;i <= n;i ++ )
    {
        int x;
        cin >> x;
        if(x == 0)root = i;
        else v[x].push_back(i);
    }
    ans = max(ans,(int)v[root].size());
    //cout << root << endl;
    dfs(root);

    if(flag)
    {
        cout << ans << " " << "no" << endl;
        for(int i = 0;i < p.size();i ++ )cout << p[i] << " ";
        cout << endl;
    }else
    {
        cout << ans << " " << "yes" <<endl;
        for(int i = 0;i < p.size();i ++ )cout << p[i] << " ";
        cout << endl;
    }
    return 0;
}