void solve (int n, int64_t k, int * answer)
{
    vector<vector<ll>> dp(n * 2, vector<ll>(n + 1));
    dp[2 * n - 1][0] = 1;
    for (int i = 2 * n - 2; i >= 0; --i)
    {
        for (int bal = 0; bal <= n; ++bal)
        {
            if (bal)
                dp[i][bal] += dp[i + 1][bal - 1];
            if (bal < n)
                dp[i][bal] += dp[i + 1][bal + 1];
        }
    }
    ll cur = k;
    int cbal = 0;
    string ans;
    ans.reserve(2 * n);
    for (int i = 0; i < 2 * n; ++i)
    {
        if (cbal > 0)
        {
            if (dp[i][cbal - 1] >= cur)
            {
                --cbal;
                ans.inb(')');
                continue;
            }
            cur -= dp[i][cbal - 1];
        }
        ++cbal;
        ans.inb('(');
    }
    vi s;
    for (int i = 0; i < 2 * n; ++i)
    {
        if (ans[i] == '(')
            s.inb(i + 1);
        else
            answer[s.back()] = i + 1, answer[i + 1] = s.back(), s.pop_back();
    }
}