n = input()
l = [int(x) for x in list(str(n))]
counter = 0
if l[0] == 1:
    l.pop(0)
    for i in range(len(l)):
        if l[i] == 3:
            counter += 1
        else:
            counter = 0
            break
if counter > 0:
    print(counter)
else:
    print(-1)