import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;
import java.util.concurrent.SynchronousQueue;

class Main {
	static int N;
	static long X;
	static long[][] A;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		N = sc.nextInt();
		A = new long[N][2];
		X = sc.nextLong();
		for (int i = 0; i < N; ++i) {
			A[i][0] = sc.nextLong();
			A[i][1] = i;
		}
		Arrays.sort(A, new Comparator<long[]>() {
			@Override
			public int compare(long[] o1, long[] o2) {
				return Long.compare(o1[1], o2[1]);
			}
		});
		int[] sum = new int[1_000_00];
		Arrays.fill(sum, -1);
		for (int i = 0; i < N - 20; ++i) {
			for (int pos = sum.length - 1; pos >= 1; --pos) {
				if (sum[pos] != -1)
					continue;
				if (pos - A[i][0] < 0)
					continue;
				if (pos - A[i][0] == 0) {
					sum[pos] = (int) A[i][1];
					continue;
				}
				if (sum[(int) (pos - A[i][0])] != -1) {
					sum[(int) pos] = (int) A[i][1];
				}
			}
		}

		for (int s = 0; s < (1 << Math.min(N, 20)); ++s) {
			long sum2 = 0;
			boolean[] ans = new boolean[N];
			for (int shift = 0; shift < Math.min(N, 20); ++shift) {
				if ((s & (1 << shift)) > 0) {
					sum2 += A[shift][0];
					ans[(int) A[shift][1]] = true;
				}
			}
			if (X - sum2 < 0)
				continue;
			if (X - sum2 == 0) {
				for (int i = 0; i < N; ++i) {
					System.out.print(ans[i] ? "o" : "x");
				}
				System.out.println();
				return;
			}
			if (X - sum2 >= 1_000_00)
				continue;
			if (sum[(int) (X - sum2)] != -1) {
				int curIdx = (int) sum[(int) (X - sum2)];
				int curSum = (int) (X - sum2);
				while (curIdx != -1) {
					ans[curIdx] = true;
					curSum -= (int) A[curIdx][0];
					curIdx = sum[curSum];
				}
				for (int i = 0; i < N; ++i) {
					System.out.print(ans[i] ? "o" : "x");
				}
				System.out.println();
				return;
			}
		}
		System.out.println("NO");
	}

	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}