def move(n, a, b, c):
    if n == 1:
        print (a,"-->",c)
    else:
        move(n-1,a,c,b)
        move(1,a,b,c)
        move(n-1,b,a,c)


n=int(input("请输入盘子数量："))
move(n, 'a', 'b', 'c')