N = int(input())
if N > 1:
    p = [2]
    for i in range(3,N+1,2):
        for s in p:
            if i%s == 0:
                break
        else:
            p += [i]
else:
    print(-1)
    exit()

p = p[::-1]
Q = [0]*len(p)
q = 0
i = len(p)-1
W = 0
while True:
    if i < 0:
        Q = [0]
        break
    elif q + p[i] == N:
        Q[i] = 1
        if W < sum(Q):
            W = sum(Q)
        Q[i] = 0
        d = Q.index(1)
        q -= p[d]
        Q[d] = 0
        i = d-1
    elif q + p[i] < N:
        Q[i] = 1
        q += p[i]
        i -= 1
    elif Q.count(1) == 0:
        break
    else:
        d = Q.index(1)
        q -= p[d]
        Q[d] = 0
        i = d-1
print(W if W != 0 else -1)