N = int(input())
dat = [0] * (N + 1)
p = []
for i in range(2,N+1):
    if dat[i] == 0:
        for j in range(i * 2,N+1,i):
            dat[j] = 1
        p.append(i)
import sys
if N == 1:
    print(-1)
    exit()
if N == 2 or N == 3:
    print(1)
    exit()
if N == 4:
    print(-1)
    exit()

n = len(p)
dp = [[-1] * (N+1) for _ in range(n)]
dp[0][p[0]] = 1
for i in range(n-1):
    for j in range(N+1):
        if dp[i][j] > 0:
            dp[i+1][j] = dp[i][j]
    for j in range(N+1):
        if dp[i][j] > 0 and j + p[i+1] <= N:
            dp[i+1][j+p[i+1]] = max(dp[i+1][j+p[i+1]],dp[i][j] + 1)
    dp[i+1][p[i+1]] = max(dp[i+1][p[i+1]],1)
print(dp[-1][-1])