"""
Nをそれぞれ異なる素数の和で表すことができる場合，
その中での最大の和の回数Mを出力してください。


dp[i] : iを異なる素数の和で表せるmax
"""
N = int(input())
INF = 10**10
U = 10**5
# is_prime = np.zeros(U,np.bool) #素数列挙(エラトステネス)
is_prime = [0] * U
is_prime[2] = 1
for i in range(3,U,2):
    is_prime[i] = 1
for p in range(3,U,2):
    if p*p > U:
        break
    if is_prime[p]:
        for i in range(p*p,U,p+p):
            is_prime[i] = 0
primes = [i for i,p in enumerate(is_prime) if p and i <= N]
dp = [[-INF] * (N+1) for i in range(len(primes)+1)]
dp[0][0] = 0

# print("len",len(primes))
for i in range(len(primes)):
    p = primes[i]
    dp[i+1][:] = dp[i][:]
    for j in range(N):
        if dp[i][j] == -INF : continue
        if j + p <= N:
            dp[i+1][j+p] = max(dp[i][j+p], dp[i][j] + 1)
ans = dp[len(primes)][N]
if ans == -INF:
    print(-1)
else:
    print(ans)