#include<stdio.h>
int main()
n=int(input().strip())
if n<0;
printf("invalid input")
else;
    nodes=[]
    for_in range(n);
    val,left,right=map(int,input().split())
input().split())
        nodes.append([val,left,right])
        stack1[0]
        stack2[1]
while stack1;
        node=stack1.pop(
            stack2.append(node)
            
            left=nodes[node][1]
            right=nodes[node][2]
            
            if left != -1:
                stack1.append(left)
                if right != -1:
                    stack2.append(right)
                    result=[nodes[i][0]for i in stack2[::-1]]
                    print(result)