import sys
if __name__ == '__main__':
    n = list(input())
    for i in range(len(n)):
        if i == 0:
            if n[i] == "1":
                continue
            else:
                print(-1)
                sys.exit(0)
        else:
            if n[i] == "3":
                continue
            else:
                print(-1)
                sys.exit(0)
    print(len(n)-1)