long long f(long long n, int k) {
  ++n;
  int bits = __builtin_popcountll(n);
  int cur = 0;
  long long ans = 0;
  while (n > 0) {
    if ((n & 1) == 1) {
      --bits;
      if (k >= bits)
        ans += c[cur][k - bits];
    }
    n >>= 1;
    ++cur;
  }
  return ans;
}