import math

def is_prime(n):
    if n == 1: return False

    for k in range(2, int(math.sqrt(n)) + 1):
        if n % k == 0:
            return False

    return True
def find(l,iter,a):
    for i in range(iter,len(l)):
        if(l[i]>=a):
            break
    return i
            
        
n=int(input())
pris=[]
prisum=[]

for i in range(2,n+1):
    if(is_prime(i)==True):
        pris.append(i)
suum=0

for i in range(0,len(pris)):
    suum+=pris[i]
    prisum.append(suum)
x=len(pris)


f=[[0]*x for i in range(n)]
if(n==1):
    print(-1)
elif(n==2 or n==3):
    print(1)
elif(n==4):
    print(-1)
elif(n>4):
    f[1][0]=1
    f[2][1]=1
    ite=0
    for i in range(4,n):
        ite=find(prisum,ite,i+1)
        for j in range(ite,min(ite+5,x)):
            if(i+1==pris[j]):
                f[i][j]=1
            else:
                z=max(f[i-pris[j]][:j])
                if(z>0):
                    f[i][j]=z+1
    mv=max(f[n-1])
    if(mv==0):
        print(-1)
    else:
        print(mv)