#!/usr/bin/env python3
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


N, X, *A = map(int, read().split())
B = sorted(A)


def dfs(B, S):
    if sum(B) < S:
        return False
    if sum(B) == S:
        return B.copy()
    x = B.pop()
    if x < S:
        res = dfs(B, S - x)
        if res:
            return res + [x]
    res = dfs(B, S)
    B.append(x)
    return res


C = dfs(B, X)
if C:
    C.sort()
    i = 0
    res = set(range(N))
    answer = ['x'] * N
    for c in C:
        for i in res:
            if A[i] == c:
                break
        res.remove(i)
        answer[i] = 'o'
    print(''.join(answer))
else:
    print('No')