Codeforces Round #388 (Div. 2) C. Voting 贪心

题目：

C. Voting

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

There are n employees in Alternative Cake Manufacturing (ACM). They are now voting on some very important question and the leading world media are trying to predict the outcome of the vote.

Each of the employees belongs to one of two fractions: depublicans or remocrats, and these two fractions have opposite opinions on what should be the outcome of the vote. The voting procedure is rather complicated:

1. Each of n employees makes a statement. They make statements one by one starting from employees 1and finishing with employee n. If at the moment when it's time for the i-th employee to make a statement he no longer has the right to vote, he just skips his turn (and no longer takes part in this voting).
2. When employee makes a statement, he can do nothing or declare that one of the other employees no longer has a right to vote. It's allowed to deny from voting people who already made the statement or people who are only waiting to do so. If someone is denied from voting he no longer participates in the voting till the very end.
3. When all employees are done with their statements, the procedure repeats: again, each employees starting from 1 and finishing with n who are still eligible to vote make their statements.
4. The process repeats until there is only one employee eligible to vote remaining and he determines the outcome of the whole voting. Of course, he votes for the decision suitable for his fraction.

You know the order employees are going to vote and that they behave optimal (and they also know the order and who belongs to which fraction). Predict the outcome of the vote.

Input

The first line of the input contains a single integer n (1 ≤ n ≤ 200 000) — the number of employees.

The next line contains n characters. The i-th character is 'D' if the i-th employee is from depublicans fraction or 'R' if he is from remocrats.

Output

Print 'D' if the outcome of the vote will be suitable for depublicans and 'R' if remocrats will win.

Examples

input

5DDRRR

output

D

input

6DDRRRR

output

R

Note

Consider one of the voting scenarios for the first sample:

1. Employee 1 denies employee 5 to vote.
2. Employee 2 denies employee 3 to vote.
3. Employee 3 has no right to vote and skips his turn (he was denied by employee 2).
4. Employee 4 denies employee 2 to vote.
5. Employee 5 has no right to vote and skips his turn (he was denied by employee 1).
6. Employee 1 denies employee 4.
7. Only employee 1 now has the right to vote so the voting ends with the victory of depublicans.

这个题目打virtual contest 时没有读懂题，然后去看了看题解报告，知道真相的我眼泪掉下来，就是每个人按顺序，可以踢一个人或者啥都不做，问最后剩那个帮派。立下flag，以后再也不用Google翻译整篇文章了，自己慢慢读题吧，顺便提高一下阅读能力。TAT

贪心策略，每次踢离他最近的敌方的人，为什么，因为这样的话，例如DRDR，可以减少自己方的一个人的伤亡，同时踢掉敌方的一个人。贪心嘛，就是要脑洞大，胆大心细。用队列来实现，相对顺序用序号来实现。

code：

#include<cstdio>
#include<queue>
using namespace std;
queue<int>D,R;
int main(){
    int n;scanf("%d",&n);getchar();
    for(int i=0;i<n;++i){
        char ch=getchar();
        if(ch=='D')D.push(i);
        else R.push(i);
    }
    //当某一队被踢干净就胜利了
    while(!D.empty()&&!R.empty()){
        int a=D.front(),b=R.front();
        D.pop();R.pop();
        if(a<b)D.push(a+n);//a在b的前面，a把b踢了，a进入下一轮，用a+n表示
        else R.push(b+n);//同理
    }
    if(D.empty())putchar('R');
    else putchar('D');
}