CF1440A.Buy the String

You are given four integers $n$, $c_0$, $c_1$ and $h$ and a binary string $s$ of length $n$.

A binary string is a string consisting of characters $0$ and $1$.

You can change any character of the string $s$ (the string should be still binary after the change). You should pay $h$ coins for each change.

After some changes (possibly zero) you want to buy the string. To buy the string you should buy all its characters. To buy the character $0$ you should pay $c_0$ coins, to buy the character $1$ you should pay $c_1$ coins.

Find the minimum number of coins needed to buy the string.

给你四个整数 $n$、$c_0$、$c_1$ 和 $h$，以及一个长度为 $n$ 的二进制字符串 $s$。

二进制字符串是指仅由字符 $0$ 和 $1$ 组成的字符串。

你可以修改字符串 $s$ 中的任意字符（修改后字符串仍需保持为二进制字符串）。每次修改需花费 $h$ 枚硬币。

在进行若干次（可能为零次）修改之后，你需要购买该字符串。购买字符串意味着购买其所有字符：购买字符 $0$ 需花费 $c_0$ 枚硬币，购买字符 $1$ 需花费 $c_1$ 枚硬币。

求购买该字符串所需的最少硬币数量。

The first line contains a single integer $t$ ($1 \leq t \leq 10$) — the number of test cases. Next $2t$ lines contain descriptions of test cases.

The first line of the description of each test case contains four integers $n$, $c_{0}$, $c_{1}$, $h$ ($1 \leq n, c_{0}, c_{1}, h \leq 1000$).

The second line of the description of each test case contains the binary string $s$ of length $n$.

第一行包含一个整数 $t$（$1 \leq t \leq 10$），表示测试用例的数量。接下来的 $2t$ 行包含各测试用例的描述。

每个测试用例描述的第一行包含四个整数 $n$、$c_{0}$、$c_{1}$、$h$（$1 \leq n, c_{0}, c_{1}, h \leq 1000$）。

每个测试用例描述的第二行包含一个长度为 $n$ 的二进制字符串 $s$。

For each test case print a single integer — the minimum number of coins needed to buy the string.

对于每个测试用例，输出一个整数——购买该字符串所需的最少硬币数量。

In the first test case, you can buy all characters and pay $3$ coins, because both characters $0$ and $1$ costs $1$ coin.

In the second test case, you can firstly change $2$-nd and $4$-th symbols of the string from $1$ to $0$ and pay $2$ coins for that. Your string will be $00000$. After that, you can buy the string and pay $5 \cdot 10 = 50$ coins for that. The total number of coins paid will be $2 + 50 = 52$.

在第一个测试用例中，你可以购买所有字符，花费 $3$ 枚硬币，因为字符 $0$ 和 $1$ 的价格均为 $1$ 枚硬币。

在第二个测试用例中，你可以首先将字符串的第 $2$ 个和第 $4$ 个字符由 $1$ 改为 $0$，为此花费 $2$ 枚硬币。此时你的字符串变为 $00000$。之后，你可以购买该字符串，为此花费 $5 \cdot 10 = 50$ 枚硬币。总共花费的硬币数为 $2 + 50 = 52$。