# ---
# title: 521. Longest Uncommon Subsequence I
# id: problem521
# author: Tian Jun
# date: 2020-10-31
# difficulty: Easy
# categories: String, Brainteaser
# link: <https://leetcode.com/problems/longest-uncommon-subsequence-i/description/>
# hidden: true
# ---
# 
# Given two strings `a` and `b`, find the length of the  **longest uncommon
# subsequence**  between them.
# 
# A  **subsequence**  of a string `s` is a string that can be obtained after
# deleting any number of characters from `s`. For example, `"abc"` is a
# subsequence of `"aebdc"` because you can delete the underlined characters in
# `"a _e_ b _d_ c"` to get `"abc"`. Other subsequences of `"aebdc"` include
# `"aebdc"`, `"aeb"`, and `""` (empty string).
# 
# An  **uncommon subsequence**  between two strings is a string that is a
# **subsequence of one  but not the other**.
# 
# Return _the length of the **longest uncommon subsequence**  between `a` and
# `b`_. If the longest uncommon subsequence doesn't exist, return `-1`.
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: a = "aba", b = "cdc"
#     Output: 3
#     Explanation: One longest uncommon subsequence is "aba" because "aba" is a subsequence of "aba" but not "cdc".
#     Note that "cdc" is also a longest uncommon subsequence.
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: a = "aaa", b = "bbb"
#     Output: 3
#     Explanation:  The longest uncommon subsequences are "aaa" and "bbb".
#     
# 
# **Example 3:**
# 
#     
#     
#     Input: a = "aaa", b = "aaa"
#     Output: -1
#     Explanation:  Every subsequence of string a is also a subsequence of string b. Similarly, every subsequence of string b is also a subsequence of string a.
#     
# 
# 
# 
# **Constraints:**
# 
#   * `1 <= a.length, b.length <= 100`
#   * `a` and `b` consist of lower-case English letters.
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
