Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
	)

var scanner = bufio.NewScanner(os.Stdin)
const INF = 0x7FFFFFFF

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		n, _ := strconv.Atoi(buf[0])
		m, _ := strconv.Atoi(buf[1])
		if n == 0 && m == 0 {
			break
		}
		chairs := make([]string, n)
		for i := range chairs {
			chairs[i] = "#"
		}
		sit := func(who string) {
			if who == "A" {
				chairs[getStringIndex(chairs, "#")] = "A" // A国の人は左から見て行って空いている席を見つけ次第座る
				// log.Println(chairs)
			} else if who == "B" {
				f := true
				for i := n-1; i > -1; i-- {
					// B国の人はA国人の隣以外で、右端から空いている椅子に座る
					if chairs[i] == "#" && (i == 0 || chairs[i-1] != "A") && (i == n-1 || chairs[i+1] != "A") {
								chairs[i] = "B"
								f = false
								break
					}
				}
				// A国人の隣しか空いていない場合、我慢して左端から空いている椅子に座る
				if f {
					chairs[getStringIndex(chairs, "#")] = "B"
				}
				// log.Println(chairs)
			} else if who == "C" { // C国人は人の隣に座りたい
				for i := 0; i < n; i++ {
					if chairs[i] != "#" {
						if i + 1 <= n-1 && chairs[i+1] == "#" {
							chairs[i+1] = "C"
							break
						} else if i - 1 >= 0 && chairs[i-1] == "#" {
							chairs[i-1] = "C"
							break
						}
					}
				}
				// log.Println(chairs)
			} else { // who == "D"
				// D国の人は人から離れて座りたい
				// どうしても誰かの隣に座らなければならない場合、その中で一番左側にある椅子に座る
				scores := make([]int, n)
				for i := range scores {
					scores[i] = INF
				}
				for i, v := range chairs {
					if v == "#" {
						scores[i]++
					}
				}
				for i := n-1; i > -1; i-- {
					tmp := 0
					if chairs[i] == "#" {
						tmp++
					} else {
						tmp = 0
					}
					scores[i] = min(scores[i], tmp)
				}
				chairs[getIntIndex(scores, getMax(scores))] = "D"
				// log.Println(chairs)
			}
		}
		scanner.Scan()
		if first := scanner.Text(); first == "A" || first == "D" {
			chairs[0] = first
		} else if first == "B" {
			chairs[len(chairs)-1] = "B"
		} else {
			chairs[n/2] = "C"
		}
		// log.Println(chairs)
		for i := 0; i < m-1; i++ {
			scanner.Scan()
			sit(scanner.Text())
		}
		fmt.Println(strings.Join(chairs, ""))
	}
}

func getStringIndex(chairs []string, who string) int {
	for i, v := range chairs {
		if v == who {
			return i
		}
	}
	return -1
}

func getIntIndex(scores []int, target int) int {
	for i, v := range scores {
		if v == target {
			return i
		}
	}
	return -1
}

func min(a, b int) int {
	if a > b {
		return b
	}
	return a
}

func getMax(scores []int) int {
	tmp := -1
	for _, v := range scores {
		if tmp < v {
			tmp = v
		}
	}
	return tmp
}

C++: #include<string>
#include<iostream>
#include<algorithm>

using namespace std;

const int INF=1<<15;

int main()
{
	int n,m;
	while(cin>>n>>m,n)
	{
		string s="";
		int d[100];
		for(int i=0;i<n;i++)
		{
			s+='#';
			d[i]=INF;
		}
		
		char in;
		for(int ii=0;ii<m;ii++)
		{
			cin>>in;
			if(in=='A')
			{
				for(int i=0;i<n;i++)if(s[i]=='#')
				{
					s[i]='A';
					d[i]=0;
					for(int j=i-1;j>=0;j--)
					{
						if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
						else break;
					}
					for(int j=i+1;j<n;j++)
					{
						if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
						else break;
					}
					break;
				}
			}
			else if(in=='B')
			{
				bool flag=false;
				for(int i=n-1;i>=0;i--)
				{
					if(s[i]=='#')
					{
						if(i==n-1&&s[i-1]!='A')
						{
							s[i]='B';
							d[i]=0;
							for(int j=i-1;j>=0;j--)
							{
								if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
								else break;
							}
							for(int j=i+1;j<n;j++)
							{
								if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
								else break;
							}
							flag=true;
							break;
						}
						else if(i==0&&s[i+1]!='A')
						{
							s[i]='B';
							d[i]=0;
							for(int j=i-1;j>=0;j--)
							{
								if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
								else break;
							}
							for(int j=i+1;j<n;j++)
							{
								if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
								else break;
							}
							flag=true;
							break;
						}
						else if(s[i-1]!='A'&&s[i+1]!='A')
						{
							s[i]='B';
							d[i]=0;
							for(int j=i-1;j>=0;j--)
							{
								if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
								else break;
							}
							for(int j=i+1;j<n;j++)
							{
								if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
								else break;
							}
							flag=true;
							break;
						}
					}
				}
				if(!flag)
				{
					for(int i=n-1;i>=0;i--)if(s[i]=='#')
					{
						s[i]='B';
							d[i]=0;
						for(int j=i-1;j>=0;j--)
						{
							if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
							else break;
						}
						for(int j=i+1;j<n;j++)
						{
							if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
							else break;
						}
						break;
					}
				}
			}
			else if(in=='C')
			{
				bool flag=false;
				for(int i=0;i<n;i++)
				{
					if(s[i]!='#')
					{
						if(i==0&&s[i+1]=='#')
						{
							s[i+1]='C';
							d[i+1]=0;
							for(int j=i;j>=0;j--)
							{
								if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
								else break;
							}
							for(int j=i+2;j<n;j++)
							{
								if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
								else break;
							}
							flag=true;
							break;
						}
						else if(i==n-1&&s[i-1]=='#')
						{
							s[i-1]='C';
							d[i-1]=0;
							for(int j=i-2;j>=0;j--)
							{
								if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
								else break;
							}
							for(int j=i;j<n;j++)
							{
								if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
								else break;
							}
							flag=true;
							break;
						}
						else
						{
							if(s[i-1]=='#')
							{
								s[i-1]='C';
								d[i-1]=0;
								for(int j=i-2;j>=0;j--)
								{
									if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
									else break;
								}
								for(int j=i;j<n;j++)
								{
									if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
									else break;
								}
								flag=true;
								break;
							}
							if(s[i+1]=='#')
							{
								s[i+1]='C';
								d[i+1]=0;
								for(int j=i;j>=0;j--)
								{
									if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
									else break;
								}
								for(int j=i+2;j<n;j++)
								{
									if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
									else break;
								}
								flag=true;
								break;
							}
						}
					}
				}
				if(!flag)
				{
					s[n/2]='C';
					d[n/2]=0;
					for(int j=n/2-1;j>=0;j--)
					{
						if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
						else break;
					}
					for(int j=n/2+1;j<n;j++)
					{
						if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
						else break;
					}
				}
			}
			else
			{
				int ma=0;
				for(int i=1;i<n;i++)
				{
					if(d[ma]<d[i])ma=i;
				}
				s[ma]='D';
				d[ma]=0;
				for(int j=ma-1;j>=0;j--)
				{
					if(d[j]>d[j+1]+1)d[j]=d[j+1]+1;
					else break;
				}
				for(int j=ma+1;j<n;j++)
				{
					if(d[j]>d[j-1]+1)d[j]=d[j-1]+1;
					else break;
				}
			}
		}
		
		cout<<s<<endl;
	}
	
	return 0;
}