public class PrefixTree {
    private PrefixTree left;
    private PrefixTree rigth;
    private char character;

    public PrefixTree(PrefixTree left, PrefixTree rigth, char character) {
        this.left = left;
        this.rigth = rigth;
        this.character = character;
    }

    public void print() {
        System.out.print(this.character);
        if (this.left != null) {
            this.left.print();
        }
        if (this.rigth != null) {
            this.rigth.print();
        }
    }

    public static void main(String[] args) {
        // 1. Распечатать дерево из задания
    }
}