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
while True:
    if i >= 0:
        if q + p[i] == N:
            Q[i] = 1
            break
        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
    else:
        Q = [0]
        break
print(sum(Q) if sum(Q) != 0 else -1)