//complete binary tree完全二叉树   indices指标指数

//For each case, print in one line YES and the index of the last node if the tree is a complete binary tree
//对于每种情况，如果树是完整的二叉树，请在一行中打印“是”和最后一个节点的索引
//or NO and the index of the root if not. 
//否则打印“否”和根的索引

//Then N lines follow, each corresponds to a node, and gives the indices of the left and right children of the node.
//接下来是N行，每行对应一个节点，并给出节点左右子节点的索引。
#include<iostream>
#include<algorithm>
#include<cstring>

using namespace std;

const int N = 25;

int n;
int l[N],r[N];
bool has_father[N];//记录每个点是否有父节点，没有父节点的即为根节点
int maxk,lastid;

void dfs(int root, int k)
{
    if(maxk < k)
    {
        lastid = root;
        maxk = k;
    }
    if(l[root] != -1) dfs(l[root], 2 * k);     //左孩子
    if(r[root] != -1) dfs(r[root], 2 * k + 1); //右孩子
}

int main()
{
    cin>>n;

    memset(l,-1,sizeof l);
    memset(r,-1,sizeof r);

    for(int i = 0; i<n; i++)
    {
        string a,b;
        cin>>a>>b;
        if(a!="-") l[i] = stoi(a),has_father[l[i]] = true;
        if(b!="-") r[i] = stoi(b),has_father[r[i]] = true;
    }

    int root;
    while(has_father[root]) root++;

    dfs(root, 1);
    if(maxk > n) cout << "NO " << root << endl;
    else cout << "YES " << lastid << endl;
}