//counting dp[mask].

for (int i = 0; i < (1 << n); ++i) {
    vector <int> bit; //bits of our num
    if (bit.size() <= k) continue;
    for (int b1: bit) {
        int min_cost = INF;
        for (int b2: bit) {
            if (b1 == b2) continue
            min_cost = min(min_cost, cost[b1][b2]);
        }
        dp[i] = min(dp[i], dp[i - (1 << b1)] + min_cost);
    }
}
cout << dp[(1 << n) - 1] << endl;