#include #include #include #include template struct Edge { int src, dst; Cost cost; Edge(int src = -1, int dst = -1, Cost cost = 1) : src(src), dst(dst), cost(cost){}; bool operator<(const Edge& e) const { return this->cost < e.cost; } bool operator>(const Edge& e) const { return this->cost > e.cost; } }; template struct Graph { std::vector>> graph; Graph(int n = 0) : graph(n) {} void span(bool direct, int src, int dst, Cost cost = 1) { graph[src].emplace_back(src, dst, cost); if (!direct) graph[dst].emplace_back(dst, src, cost); } std::vector>& operator[](int v) { return graph[v]; } std::vector> operator[](int v) const { return graph[v]; } int size() const { return graph.size(); } }; template std::vector bfs(const Graph& graph, int s) { std::vector dist(graph.size(), -1); dist[s] = 0; std::queue que; que.push(s); while (!que.empty()) { int v = que.front(); que.pop(); for (const auto& e : graph[v]) { if (dist[e.dst] != -1) continue; dist[e.dst] = dist[v] + e.cost; que.push(e.dst); } } return dist; } void solve() { int n, p; std::cin >> n >> p; Graph<> graph(n + 1); for (int d = 2; d <= n; ++d) { for (int i = d; i + d <= n; i += d) { graph.span(false, i, i + d); } } auto ds = bfs(graph, p); std::cout << std::count_if(ds.begin(), ds.end(), [](int d) { return d != -1; }) << std::endl; } int main() { std::cin.tie(nullptr); std::ios::sync_with_stdio(false); solve(); return 0; }