def solve():
    n = list(input())
    if len(n) == 1:
        print(-1)
        return
    for i, x in enumerate(n):
        if i == 0 and x != "1":
            print(-1)
            return
        if i > 0 and x != "3":
            print(-1)
            return
    print(len(n)-1)
solve()