import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.stdio;

void main() {
    auto s = readln.split;
    auto N = s[0].to!int;
    auto X = s[1].to!long;
    auto A = readln.split.map!(to!long).array;

    int[][long] dp;
    foreach (i; 0..N) {
        foreach (k; dp.keys) {
            if (A[i]+k <= X && !(A[i]+k in dp))
                dp[A[i]+k] = (dp[k] ~ i);
        }
        if (A[i] <= X && !(A[i] in dp)) dp[A[i]] = [i];
    }

    string ans = "";
    if (X in dp) {
        foreach (i; 0..N) {
            ans ~= (find(dp[X], i).empty) ? "x" : "o";
        }
    }
    else {
        ans = "NO";
    }

    ans.writeln;
}