import sys read = sys.stdin.buffer.read readline = sys.stdin.buffer.readline readlines = sys.stdin.buffer.readlines import numpy as np N, X = map(int, readline().split()) A = list(map(int, read().split())) K = 10 ** 5 low = [] high = [] for x in A: if x <= K: low.append(x) else: high.append(x) L = len(low) H = len(high) dpl = [None] * (L + 1) dpl[0] = np.zeros(1, np.int64) for i, x in enumerate(low, 1): dp = np.full(len(dpl[i - 1]) + x, -1, np.int32) dp[:-x] = dpl[i - 1] dp[x:][dpl[i - 1] >= 0] = i dpl[i] = dp dph = np.zeros(1 << H, np.int64) for i, x in enumerate(high): dph[1 << i: 1 << i + 1] = dph[: 1 << i] + x nums = X - dph nums = nums[(0 <= nums) & (nums < len(dpl[-1]))] nums = nums[dpl[-1][nums] >= 0] if not len(nums): print('No') exit() low_sum = nums[0] high_sum = X - low_sum # 復元 low_ind = [] high_ind = [] n = len(low) while low_sum: n = dpl[n][low_sum] - 1 low_sum -= A[n] low_ind.append(n) i = np.where(dph == high_sum)[0] for j in range(H): if i & (1 << j): high_ind.append(j) nums = [low[i] for i in low_ind] + [high[i] for i in high_ind] for x in nums: i = A.index(x) A[i] = 0 answer = ''.join('x' if x else 'o' for x in A) print(answer)