N = 20000 + 1
furui = [1 for i in range(N)]
furui[0] = furui[1] = 0
for i in range(2, int(N ** 0.5) + 1):
	if furui[i]:
		for j in range(i * i, N, i):
			furui[j] = 0
primes = [i for i, x in enumerate(furui) if x == 1]
dp = [[-1 for i in range(N)] for j in primes]
for i, p in enumerate(primes):
	dp[i][p] = 1
for i, p in enumerate(primes):
	if i == 0: continue
	for m in range(N):
		if m - p <= 0 or dp[i - 1][m - p] == -1:
			dp[i][m] = max(dp[i - 1][m], dp[i][m])
		else:
			dp[i][m] = max(dp[i - 1][m], dp[i - 1][m - p] + 1, dp[i][m]
			)
n = int(input())
print(dp[-1][n])