using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	const double eps=1e-11;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		var g=sc.Arr(s[0],()=>sc.S);
		var h=new char[]{'X','X','X'};
		var d=new char[s[0]][];
		var z=new int[]{mod,mod,mod};
		var f=new int[s[0]][];
		for(int i = s[0]-1;i>=0;i--) {
			var t=g[i];
			d[i]=new char[3];
			f[i]=new int[3];
			for(int j = 0;j<3;j++) {
				d[i][j]=h[j];
				f[i][j]=z[j];
			}
			h[t[0]-65]=t[1];
			h[t[1]-65]=t[0];
			z[t[0]-65]=i;
			z[t[1]-65]=i;
		}
		StringBuilder sb=new StringBuilder();
		for(int i = 0;i<s[0];i++) {
			var t=g[i];
			if(s[t[0]-64]>s[t[1]-64]){
				s[t[0]-64]--;
				s[t[1]-64]++;
				sb.Append(t[1]+"\n");
			}
			else if(s[t[0]-64]<s[t[1]-64]){
				s[t[0]-64]++;
				s[t[1]-64]--;
				sb.Append(t[0]+"\n");
			}
			else if(f[i][t[0]-65]<f[i][t[1]-65]){
				s[t[0]-64]++;
				s[t[1]-64]--;
				sb.Append(t[0]+"\n");
			}
			else{
				s[t[0]-64]--;
				s[t[1]-64]++;
				sb.Append(t[1]+"\n");
			}
			if(s[t[0]-64]<0||s[t[1]-64]<0){
				Console.WriteLine("No");
				return;
			}
		}
		Console.WriteLine("Yes");
		Console.Write(sb);
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);}
	public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);}
	public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),double.Parse);}
	public double[] Da3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}

Measured memory_bytes: 47836