#include<iostream>
#include<string>
#include<vector>
#include<queue>
#include<stack>
#include<map>
#include<set>
#include<algorithm>
#include<functional>
#include<cstdio>
#include<cstdlib>
#include<cmath>
using namespace std;

#define mind(a,b) (a>b?b:a)
#define maxd(a,b) (a>b?a:b)
#define absd(x) (x<0?-(x):x)
#define pow2(x) ((x)*(x))
#define rep(i,n) for(int i=0; i<n; ++i)
#define repr(i,n) for(int i=n-1; i>=0; --i)
#define repl(i,s,n) for(int i=s; i<=n; ++i)
#define replr(i,s,n) for(int i=n; i>=s; --i)
#define repf(i,s,n,j) for(int i=s; i<=n; i+=j)
#define repe(e,obj) for(auto e : obj)

#define SP << " " <<
#define COL << " : " <<
#define COM << ", " <<
#define ARR << " -> " <<
#define PNT(STR) cout << STR << endl
#define POS(X,Y) "(" << X << ", " << Y << ")"
#define DEB(A) " (" << #A << ") " << A
#define DEBREP(i,n,val) for(int i=0; i<n; ++i) cout << val << " "; cout << endl
#define ALL(V) (V).begin(), (V).end()
#define INF 1000000007
#define INFLL 10000000000000000007LL
#define EPS 1e-9

typedef unsigned int uint;
typedef unsigned long ulong;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
//typedef pair<ll, ll> P;
typedef pair<P, int> PI;
typedef pair<int, P> IP;
typedef pair<P, P> PP;
typedef priority_queue<P, vector<P>, greater<P> > pvqueue;

#define N 110

#define W 100005
ll n, x;
ll a[N];

struct Value {
  Value(ll x, string s) : x(x), s(s) {}
  Value() : x(0), s("") {}
  ll x;
  string s;

  bool operator<(const Value& v) const {
    return x < v.x;
  }
};

Value dp[W];

int main() {
  cin >> n >> x;
  rep(i, n) cin >> a[i];

  if(n < 30) {
    set<Value> p0;
    p0.insert(Value(0, ""));
    rep(i, n/2) {
      set<Value> p0_2;
      for(set<Value>::iterator it = p0.begin(); it != p0.end(); ++it) {
        Value v = *it;
        p0_2.insert(Value(v.x,v.s+"x"));
        p0_2.insert(Value(v.x+a[i], v.s+"o"));
      }
      p0 = p0_2;
    }
    set<Value> p1;
    p1.insert(Value(0, ""));
    repl(i, n/2, n-1) {
      set<Value> p1_2;
      for(set<Value>::iterator it = p1.begin(); it != p1.end(); ++it) {
        Value v = *it;
        p1_2.insert(Value(v.x, v.s+"x"));
        p1_2.insert(Value(v.x+a[i], v.s+"o"));
      }
      p1 = p1_2;
    }

    set<Value>::iterator p0_it = p0.begin();
    set<Value>::reverse_iterator p1_rit = p1.rbegin();
    while(p0_it != p0.end() && p1_rit != p1.rend()) {
      Value v0 = *p0_it, v1 = *p1_rit;
      if(v0.x + v1.x == x) {
        cout << v0.s + v1.s << endl;
        exit(0);
      }
      ++p0_it;
      while(p0_it != p0.end() && p1_rit != p1.rend() && (*p0_it).x + (*p1_rit).x > x) ++p1_rit;
    }
    cout << "No" << endl;
  } else {
    dp[0].x = 1;
    rep(i, n) {
      replr(j, a[i], W-1) {
        if(!dp[j].x && dp[j-a[i]].x) {
          dp[j].x = 1;
          dp[j].s = dp[j-a[i]].s + "o";
        } else {
          dp[j].s += "x";
        }
      }
      rep(j, a[i]) {
        dp[j].s += "x";
      }
    }
    if(dp[x].x) {
      cout << dp[x].s << endl;
    } else {
      cout << "No" << endl;
    }
  }
  return 0;
}