题解 | #杨辉三角的变形#

while True:
    try:
        x1 = int(input())
        if x1 == 1 or x1 == 2:
            print(-1)
        elif (x1+1) % 2 == 0:
            print(2)
        elif x1 % 4 == 0:
            print(3)
        elif (x1-2) % 4 == 0:
            print(4)
    except:
        break