# 直接用行数n模4，做出判断，n==1或n==2属于特殊情况，特殊处理
n = int(input())
if n ==1 or n ==2:
    print(-1)
elif n % 4 == 1 or n % 4 == 3:
    print(2)
elif n % 4 == 0:
    print(3)
else:
    print(4)