func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, k, l, r, m;     cin >> n >> k;     deque<pair<int, int>> bfs;     vector<int> lines;     vector<int> ans(n);     --k;     bfs.push_back({0, n});     while (!bfs.empty()) {       l = bfs[0].first;       r = bfs[0].second;       m = (l + r) / 2;       bfs.pop_front();       if (k > 0 && r - l > 1) {         k -= 2;         lines.push_back(m);         bfs.push_back({l, m});         bfs.push_back({m, r});       }     }     if (k != 0) {       cout << -1;       return 0;     } else {       int num = 1;       lines.push_back(0);       lines.push_back(n);       sort(lines.begin(), lines.end());       for (int i = lines.size() - 2; i >= 0; --i) {         for (int j = lines[i]; j != lines[i + 1]; ++j) {           ans[j] = num;           ++num;         }       }     }     for (int i = 0; i != n; ++i) {       cout << ans[i] <<    ;     }     return 0;   }   