def solution(n):
    nodes = [1]
    for i in range(n-1):
        # print(i, nodes)
        next_nodes = []
        for node in nodes:
            next_nodes += [j for j in range(1, node + 2)]
        nodes = next_nodes
    # print(i+1, nodes)
    return len(nodes)

'''
()
()() (())
()()() (())() (()()) ()(()) ((()))
()()()() (())()() (()())() (()()()) ()(())() ((()))() ((())()) ()(()()) ((()())) ()()(()) (())(()) (()(())) ()((())) (((())))

1
11 2
111 21 3 12 3
1111 211 31 4 121 31 4 13 4 112 22 4 13 4


1
2 1
3 2 1 2 1
4 3 2 1 3 2 1 2 1 3 2 1 2 1
'''