n, m = map(int, input().split()) sum = 0 for i in range(n, m + 1): s = str(i) l = len(s) if s[l - 1] == '4': sum += 1 continue for j in range(0, l - 1): if (s[j] == '6' and s[j + 1] == '2') or s[j] == '4': sum += 1 break print(m - n + 1 - sum)