Leftist-Heap

struct Node // min-heap on int64
{
    Node *left;
    Node *right;
    ll x;
    int d;

    Node(ll x):
        left(NULL),
        right(NULL),
        x(x),
        d(1) {}
};

int d(Node *v)
{
    if (v == NULL)
        return 0;
    else
        return v->d;
}

Node* merge(Node *a, Node *b)
{
    if (a == NULL)
        return b;
    if (b == NULL)
        return a;
    if (a->x > b->x)
        swap(a, b);
    a->right = merge(a->right, b);
    if (d(a->right) > d(a->left))
        swap(a->right, a->left);
    a->d = d(a->right) + 1;
    return a;
}

Node* push(Node *root, ll x)
{
    return merge(root, new Node(x));
}

Node* pop(Node *root)
{
    return merge(root->left, root->right);
}

ll min(Node *root)
{
    return root->x;
}