import sys

def yang(n):
    if n==1 or n==2:
        return -1
    elif n%4==3:
        return 2
    elif n%4==0:
        return 3
    elif n%4==1:
        return 2
    elif n%4==2:
        return 4

for line in sys.stdin:
    n=int(line[:-1])
    print(yang(n))