Replace

AtCoder

IDabc261_g

Time2000ms

Memory256MB

Difficulty—

You are given two strings $S$ and $T$ consisting of lowercase English letters. Takahashi starts with the string $S$. He can perform $K$ kinds of operations any number of times in any order. The $i$\-th operation is the following: > Pay a cost of $1$. Then, if the current string contains the **character** $C_i$, choose one of its occurrences and replace it with the **string** $A_i$. Otherwise, do nothing. Find the minimum total cost needed to make the string equal $T$. If it is impossible to do so, print $-1$. ## Constraints * $1\leq |S|\leq |T|\leq 50$ * $1\leq K\leq 50$ * $C_i$ is `a`, `b`,$\ldots$, or `z`. * $1\leq |A_i|\leq 50$ * $S$, $T$, and $A_i$ are strings consisting of lowercase English letters. * $C_i\neq A_i$, regarding $C_i$ as a string of length $1$. * All pairs $(C_i,A_i)$ are distinct. ## Input Input is given from Standard Input in the following format: $S$ $T$ $K$ $C_1$ $A_1$ $C_2$ $A_2$ $\vdots$ $C_K$ $A_K$ [samples]

Samples

Input #1

ab
cbca
3
a b
b ca
a efg

Output #1

4

Starting with $S=$`ab`, Takahashi can make $T=$`cbca` in four operations as follows:

*   Replace the $1$\-st character `a` in `ab` with `b` (Operation of the $1$\-st kind). The string is now `bb`.
*   Replace the $2$\-nd character `b` in `bb` with `ca` (Operation of the $2$\-nd kind). The string is now `bca`.
*   Replace the $1$\-st character `b` in `bca` with `ca` (Operation of the $2$\-nd kind). The string is now `caca`.
*   Replace the $2$\-nd character `a` in `caca` with `b` (Operation of the $1$\-st kind). The string is now `cbca`.

Each operation incurs a cost of $1$, for a total of $4$, which is the minimum possible.

Input #2

a
aaaaa
2
a aa
a aaa

Output #2

2

Two operations `a` $\to$ `aaa` $\to$ `aaaaa` incur a cost of $2$, which is the minimum possible.

Input #3

a
z
1
a abc

Output #3

\-1

No sequence of operations makes $T=$`z` from $S=$`a`.

API Response (JSON)

{
  "problem": {
    "name": "Replace",
    "description": {
      "content": "You are given two strings $S$ and $T$ consisting of lowercase English letters. Takahashi starts with the string $S$. He can perform $K$ kinds of operations any number of times in any order.   The $i$\\",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc261_g"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "You are given two strings $S$ and $T$ consisting of lowercase English letters.\nTakahashi starts with the string $S$. He can perform $K$ kinds of operations any number of times in any order.  \nThe $i$\\...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments