package no332;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long x = sc.nextLong();
		ArrayList<Pair> a = new ArrayList<>(); //i,a
		for(int i=0;i<n;i++) {
			int aa = sc.nextInt();
			a.add(new Pair(i,aa));
		}
		Collections.sort(a,(xx,yy)->Integer.compare(xx.a, yy.a));
		int ones = 0;
		for(Pair p:a) {
			if (p.a == 1) {
				ones++;
			}else{
				break;
			}
		}
		int n2 = n - ones;
		int n3 = n2 / 2;
		int n4 = n2 - n3;
		ArrayList<Pair2> al = new ArrayList<>();
		for(int i=0;i<1<<n3;i++) {
			long sum = 0;
			for(int j=0;j<n3;j++) {
				if ((i>>j&1)==1) {
					sum += a.get(ones + j).a;
				}
			}
			al.add(new Pair2(i, sum));
		}
		Collections.sort(al,(xx,yy)->Long.compare(xx.sum, yy.sum));
		for(int i=0;i<1<<n4;i++) {
			long sum = 0;
			for(int j=0;j<n4;j++) {
				if ((i>>j&1)==1) {
					sum += a.get(ones + n3 + j).a;
				}
			}
			if (sum > x) {
				continue;
			}
			long key = x - sum;
			int l = 0;
			int r = al.size();
			while(l + 1 < r) {
				int c = (l + r) >>> 1;
				if (al.get(c).sum <= key) {
					l = c;
				}else{
					r = c;
				}
			}
			if (sum + al.get(l).sum + ones >= x) {
				boolean[] ans = new boolean[n];
				for(int j=0;j<n3;j++) {
					if ((al.get(l).mask >> j & 1) == 1) {
						ans[a.get(ones + j).i] = true;
					}
				}
				for(int j=0;j<n4;j++) {
					if ((i>>j&1)==1) {
						ans[a.get(ones + n3 + j).i] = true;
					}
				}
				for(int j=0;j<x-sum-al.get(l).sum;j++) {
					ans[j] = true;
				}
				StringBuilder sb = new StringBuilder();
				for(int j=0;j<n;j++) {
					sb.append(ans[j] ? 'o' : 'x');
				}
				System.out.println(sb);
				return;
			}
		}
		System.out.println("No");
	}

}
class Pair {
	int i,a;
	public Pair(int i,int a) {
		this.i = i;
		this.a = a;
	}
}
class Pair2 {
	int mask;
	long sum;
	public Pair2(int mask,long sum) {
		this.mask = mask;
		this.sum = sum;
	}
}