using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Numerics;
using BI=System.Numerics.BigInteger;

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		Pair[] AA=new Pair[N];
		for(int i=0;i<N;i++){
			AA[i]=new Pair(A[i],i);
		}
		Array.Sort(AA,(x,y)=>x.V.CompareTo(y.V));
		
		int N1=0;
		long sum1=0;
		int Vmax=1000000;
		
		for(int i=0;i<N;i++){
			if(sum1+AA[i].V>=Vmax)break;
			sum1+=AA[i].V;
			N1++;
		}
		
		int[] dp=new int[Vmax];
		for(int i=0;i<Vmax;i++){
			dp[i]=-1;
		}
		dp[0]=-10000000;
		
		for(int i=0;i<N1;i++){
			for(int j=Vmax-1;j>=0;j--){
				if(dp[j]!=-1 && dp[j+AA[i].V]==-1){
					dp[j+AA[i].V]=i;
				}
			}
		}
		int N2=N-N1;
		long[] Large=new long[1<<N2];
		Large[0]=0;
		for(int i=1;i<(1<<N2);i++){
			int msb=0;
			for(int j=30;j>=0;j--){
				if((i>>j)>0){msb=j;break;}
			}
			Large[i]=AA[N1+msb].V+Large[(i^(1<<msb))];
		}
		
		Pair[] LA=new Pair[1<<N2];
		for(int i=0;i<(1<<N2);i++){
			LA[i]=new Pair(Large[i],i);
		}
		Array.Sort(LA,(x,y)=>x.V.CompareTo(y.V));
		int tail=0;
		int head=Vmax-1;
		while(head>=0){
			if(dp[head]==-1){
				head--;
				continue;
			}
			while(tail<(1<<N2)-1 && LA[tail].V+head<X)tail++;
			if(LA[tail].V+head==X){
				char[] Ans=new char[N];
				for(int ii=0;ii<N;ii++)Ans[ii]='x';
				int now=head;
				while(dp[now]>=0){
					Ans[AA[dp[now]].Idx]='o';
					now-=(int)AA[dp[now]].V;
				}
				int s=LA[tail].Idx;
				for(int ii=0;ii<30;ii++){
					if(((s>>ii)&1)==1){
						Ans[AA[ii+N1].Idx]='o';
					}
				}
				
				Console.WriteLine(new String(Ans));
				return;
			}
			head--;
		}
		
		
		
		Console.WriteLine("No");
		
	}
	class Pair{
		public long V;
		public int Idx;
		public Pair(long v,int i){
			V=v;Idx=i;
		}
	}
	
	long[] A;
	int N;
	long X;
	public Sol(){
		var d=rla();
		N=(int)d[0];
		X=d[1];
		A=rla();
	}




	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(){return Console.ReadLine().Split(' ');}
	static int[] ria(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>int.Parse(e));}
	static long[] rla(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>long.Parse(e));}
	static double[] rda(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>double.Parse(e));}
}