n=int(raw_input())
if n==1:
 print('NO\n')
elif n==2:
 print('YES\n')
else:
 for var in range(2,n):
  if n%var==0: 
   print('NO\n')
   break
  elif (n%var!=0 and var!=n-1):
   continue
  else: print('YES\n')