Shiritori

AtCoder

IDabc109_b

Time2000ms

Memory256MB

Difficulty—

Takahashi is practicing _shiritori_ alone again today. Shiritori is a game as follows: * In the first turn, a player announces any one word. * In the subsequent turns, a player announces a word that satisfies the following conditions: * That word is not announced before. * The first character of that word is the same as the last character of the last word announced. In this game, he is practicing to announce as many words as possible in ten seconds. You are given the number of words Takahashi announced, $N$, and the $i$\-th word he announced, $W_i$, for each $i$. Determine if the rules of shiritori was observed, that is, every word announced by him satisfied the conditions. ## Constraints * $N$ is an integer satisfying $2 \leq N \leq 100$. * $W_i$ is a string of length between $1$ and $10$ (inclusive) consisting of lowercase English letters. ## Input Input is given from Standard Input in the following format: $N$ $W_1$ $W_2$ $:$ $W_N$ [samples]

Samples

Input #1

4
hoge
english
hoge
enigma

Output #1

No

As `hoge` is announced multiple times, the rules of shiritori was not observed.

Input #2

9
basic
c
cpp
php
python
nadesico
ocaml
lua
assembly

Output #2

Yes

Input #3

8
a
aa
aaa
aaaa
aaaaa
aaaaaa
aaa
aaaaaaa

Output #3

No

Input #4

3
abc
arc
agc

Output #4

No

API Response (JSON)

{
  "problem": {
    "name": "Shiritori",
    "description": {
      "content": "Takahashi is practicing _shiritori_ alone again today. Shiritori is a game as follows: *   In the first turn, a player announces any one word. *   In the subsequent turns, a player announces a word t",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc109_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Takahashi is practicing _shiritori_ alone again today.\nShiritori is a game as follows:\n\n*   In the first turn, a player announces any one word.\n*   In the subsequent turns, a player announces a word t...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments