#  汉诺塔问题，把n个盘子从A搬到C，在搬动过程中可以借助B作为中转。

cnt=0                             	#统计移动次数，cnt是一个全局变量
def hanoi(n,a,b,c):
    global cnt
    if n==1:
        cnt+=1
        move(n,a,c)
    else:
        hanoi(n-1,a,c,b)
        cnt+=1
        move(n,a,c)
        hanoi(n-1,b,a,c)
def move(n,x,y):
    print("{:5d}: {:s}{:d}{:s}{:s}{:s}{:s}.".format(cnt,"Move disk ",n,"\
        from tower ",x," to tower ",y))
def main():
    print("TOWERS OF HANOI:")
    print("The problem starts with n plates on tower A.")
    print("Input the number of plates:")
    n=eval(input())
    print("The step to moving {:d} plates:".format(n))
    hanoi(n,'A','B','C')            	#借助B将n个盘子从A移至C
main()