from math import factorial, sqrt

data = {}
data[2] = 1
data[3] = 2
data[4] = 2
data[5] = 4

def is_prim(x):
    if x%2 == 0: return False
    for i in range(3, int(sqrt(x)), 2):
        if x % i == 0: return False
    return True

x = int(raw_input())

if x<=5:
    print(str(data[str(x)]))
else:
    if is_prim(x): print str(x-1)
    else: print "0"