102901: [Atcoder]ABC290 B - Qual B

Problem Statement

There were $N$ contestants in the qualification round of a programming contest. All contestants got distinct ranks.
You are given a length-$N$ string $S$, which represents whether the contestants want to participate in the final round or not. Specifically,

• if the $i$-th character of $S$ is o, the contestant ranked $i$-th in the qualification wants to participate in the final;
• if the $i$-th character of $S$ is x, the contestant ranked $i$-th in the qualification does not want to participate in the final.

Among those who want to participate in the final, $K$ contestants with the smallest ranks advance to the final.

Print a string $T$ of length $N$ that satisfies the following conditions:

• if the contestant ranked $i$-th in the qualification advances to the final, the $i$-th character of $T$ is o;
• if the contestant ranked $i$-th in the qualification does not advance to the final, the $i$-th character of $T$ is x.

Constraints

• $N$ and $K$ are integers.
• $1 \le K \le N \le 100$
• $S$ is a string of length $N$ consisting of o and x.
• $S$ has at least $K$ o's.

Input

The input is given from Standard Input in the following format:

$N$ $K$
$S$

Output

Print the answer.

Sample Input 1

10 3
oxxoxooxox

Sample Output 1

oxxoxoxxxx

In this input, $N=10$ people took part in the qualification round, and $K=3$ of them advance to the final.

• The participant who ranked $1$-st in the qualification wants to participate in the final, so the participant advances to the final. $1$ participant has advanced so far.
• The participants who ranked $2$-nd and $3$-rd in the qualification do not want to participate in the final, so the participants do not advance to the final.
• The participant who ranked $4$-th in the qualification wants to participate in the final, so the participant advances to the final. $2$ participants have advanced so far.
• The participants who ranked $5$-th in the qualification does not want to participate in the final, so the participant does not advance to the final.
• The participant who ranked $6$-th in the qualification wants to participate in the final, so the participant advances to the final. $3$ participants have advanced so far.
• Now that $3$ people have advanced to the final, no participants ranked $7$-th or lower advance to the final.

问题描述

在一个编程竞赛的资格赛中有N名选手。所有选手的排名都是不同的。

• 如果字符串S的第i个字符是o，那么在资格赛中排名i的选手想要参加决赛；
• 如果字符串S的第i个字符是x，那么在资格赛中排名i的选手不想参加决赛。

在想要参加决赛的选手中，排名最小的K名选手可以进入决赛。

输出一个长度为N的字符串T，满足以下条件：

• 如果资格赛中排名i的选手进入决赛，那么字符串T的第i个字符是o；
• 如果资格赛中排名i的选手没有进入决赛，那么字符串T的第i个字符是x。

约束

• N和K是整数。
• 1≤K≤N≤100
• S是一个长度为N的字符串，由o和x组成。
• S至少有K个o。

输入

输入将从标准输入中以以下格式给出：

$N$ $K$
$S$

输出

输出答案。

样例输入1

10 3
oxxoxooxox

样例输出1

oxxoxoxxxx

在这个输入中，有10名选手参加了资格赛，其中3名选手进入决赛。

• 在资格赛中排名1的选手想要参加决赛，所以该选手进入了决赛。到目前为止有1名选手进入了决赛。
• 在资格赛中排名2和3的选手不想参加决赛，所以这些选手没有进入决赛。
• 在资格赛中排名4的选手想要参加决赛，所以该选手进入了决赛。到目前为止有2名选手进入了决赛。
• 在资格赛中排名5的选手不想参加决赛，所以该选手没有进入决赛。
• 在资格赛中排名6的选手想要参加决赛，所以该选手进入了决赛。到目前为止有3名选手进入了决赛。
• 现在已经有3人进入了决赛，排名7或更低的选手都没有进入决赛。