import random
def solve(x):
  x=x-1
  while x%2==0:
    x>>=1
  for l in range(0,30):
    r=random.randint(1,x-1)
    t=x
    y=pow(r,t,x)
    while t!=x-1 and y!=1 and y!=x-1:
      y=(y*y)%x
      t<<=1
    if y!=x-1 and t&1==0:
      return False
  return True
a=[0,0,0,0,3,0,5,0,7,7,7,0,11,0,13,7,7,0,8,0,19,19,7,0,23,23]
x=input()
if x<26:print a[x]
else:print 14 if (x-1)%8==0 and x%2 and solve(x-8) else 8