import sys

s = input()
if s == "1":
    print(-1)
    sys.exit()
if s[0] == "1":
    for i in range(1, len(s)):
        if not s[i] == "3":
            print(-1)
            sys.exit()
    print((len(s) - 1))
else:
    print(-1)
    sys.exit()