N = input()
ans = 0
if len(N)==1 or int(N[0]) != 1:
    print("-----")
    print(len(N), N[0])
    ans = -1
else:
    for i in range(1, len(N)):
        if int(N[i]) != 3:
            ans = -1
    if ans != -1:
        ans = len(N)-1
print(ans)