class Solution
{
    public int solution(Tree node)
    {
        return countVisible(node, 0) + 1;
    }

    private int countVisible(Tree node, int current_max)
    {
        if (node == null)
            return 0;

        int count_me = current_max < node.x ? 1 : 0;
        current_max = Math.Max(current_max, node.x);

        return countVisible(node.r, current_max)
            + countVisible(node.l, current_max)
            + count_me;
    }
}