import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# md = 10**9+7
md = 998244353

n, x = LI()
aa = LI()

if n <= 20:
    sa = [(0, 0)]
    for i, a in enumerate(aa):
        s = 1 << i
        nsa = []
        for t, b in sa:
            nsa.append((s | t, a+b))
        sa += nsa

    for s,a in sa:
        if a==x:
            ans=""
            for i in range(n):
                if s>>i&1:
                    ans+="o"
                else:
                    ans+="x"
            print(ans)
            exit()

else:
    ia = sorted(enumerate(aa), key=lambda x: -x[1])
    sa = [(0, 0)]
    for i in range(20):
        s = 1 << i
        a=ia[i][1]
        nsa = []
        for t, b in sa:
            nsa.append((s | t, a+b))
        sa += nsa

    t=sum(a for _,a in  ia[20:])
    dp=[-1]*(t+1)
    dp[0]=0
    for i,a in ia[20:]:
        for j in range(t-a,-1,-1):
            if dp[j]==-1 or dp[j+a]!=-1:continue
            dp[j+a]=i

    ans=[0]*n
    for s,a in sa:
        if not 0<=x-a<=t:continue
        if dp[x-a]==-1:continue
        for j in range(n):
            if s>>j&1:
                i=ia[j][0]
                ans[i]=1
        x-=a
        while x:
            i=dp[x]
            ans[i]=1
            x-=aa[i]

        print("".join("o" if a else "x" for a in ans))
        exit()

print("No")