#異なる素数の和

# dp[depth][sum] := num

def showPrimeNum(N):
	""" N以下の素数を返すプログラム """
	is_prime_table = [0] * (N+1) 
	is_prime_table[1] = 0
	prime_list = []

	for i in range(2,N//2+1):
		if is_prime_table[i] == 0:
			j = 2 * i	#イテレータ初期化
			while (j <= N):
				is_prime_table[j] = 1
				j += i 		#掛け算より足し算の方が、計算コストが少なくて良い

	for i in range(1,N+1):
		if is_prime_table[i] == 0:
			prime_list.append(i)

	return prime_list[1:]


if __name__ == "__main__":

	INF = float('inf')

	N = int(input())
	primeNum = showPrimeNum(N)

	l = len(primeNum)

	dp = [[-INF] * (N+1) for _ in range(l+1)]

	for i in range(0,l+1):
		dp[i][0] = 0

	for i in range(1,l+1):
		for Sum in range(1,N+1):
			if Sum - primeNum[i-1] >= 0 :
				dp[i][Sum] = max([dp[i-1][Sum-primeNum[i-1]] + 1,dp[i-1][Sum]])

			else:
				dp[i][Sum] = dp[i-1][Sum]

	print(dp[l][N])