My tree-node has a missing link

I was going through the question Tree Nodes Getting Lost and thought it woudl be a good exercise to do in c++11.

I came with the code below. But the Root element is not connecting to the rest of the nodes and I can't find why.

#include <iostream>
#include <vector>
#include <array>

struct Node 
{
    int key;
    std::vector<Node> children;
    Node(int k)
    {
        key = k;
    }

    void Add(Node n)
    {
        children.push_back(n);
    }

    void display()
    {
        std::cout << "My value is " << key << std::endl;
        std::cout << "My " << children.size()  << " kid(s) are : " << std::endl;
        for( auto n : children)
        {
            n.display();
        }
    }

};

int main()
{
    constexpr int numNode = 5; // for 
    std::array<int, numNode> numbers = { 4, -1, 4, 1, 1 }; 
    std::vector<Node> nodesStorage;

    for (int i = 0 ; i < numNode ; i++)
    {
        nodesStorage.push_back(Node(i));
    }
    nodesStorage.push_back(Node(-1)); 

    for (int i = 0 ; i< numNode ; i++)
    {
        if(numbers[i] == -1) // the root
        {
            nodesStorage[numNode].Add(nodesStorage[i]);
        }
        else
        {
            nodesStorage[numbers[i]].Add(nodesStorage[i]);
        }
    }

    nodesStorage[1].display();
    nodesStorage[numNode].display();

    return 0;

}