x=100000

import math 
L=math.floor(math.sqrt(x)) # 平方根を求める

Primelist=[i for i in range(x+1)]
Primelist[1]=0 # 1は素数でないので0にする.
 
for i in Primelist:
    if i>L:
        break
    if i==0:
        continue
    for j in range(2*i,x+1,i):
        Primelist[j]=0

Primes=[Primelist[j] for j in range(x+1) if Primelist[j]!=0]
PS=set(Primes)


for a in range(2,100):
    for b in range(a+1,100):
        for c in range(b+1,100):
            for d in range(c+1,100):
                if a+b in PS and c+d in PS:
                    if not (a+c) in PS and not (a+d) in PS and not (b+c) in PS and not (b+d) in PS:
                        LIST=[a,b,c,d]
                        #print(LIST)

LIST=[2,3,6,7]

N=int(input())

for a in range(100):
    for b in range(100):
        k=a*b
        rest=N-k

        if rest<0:
            break
        for c in range(100):
            for d in range(100):
                if rest==c*d and a+b+c+d<=250:
                    ANS=[2]*a+[3]*b+[6]*c+[7]*d

                    print(len(ANS))
                    print(*ANS)

                    exit()