#include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long ll; const int MAX_N = 1000010; vector parent; vector _rank; vector _size; class UnionFind { public: UnionFind(int n) { for (int i = 0; i < n; ++i) { parent.push_back(i); _rank.push_back(0); _size.push_back(1); } } int find(int x) { if (parent[x] == x) { return x; } else { return parent[x] = find(parent[x]); } } void unite(int x, int y) { x = find(x); y = find(y); if (x == y) return; if (_rank[x] < _rank[y]) { parent[x] = y; _size[y] += _size[x]; } else { parent[y] = x; _size[x] += _size[y]; if (_rank[x] == _rank[y]) ++_rank[x]; } } bool same(int x, int y) { return find(x) == find(y); } int size(int x) { return _size[find(x)]; } }; int main() { int N, P; cin >> N >> P; UnionFind uf(MAX_N); bool visited[MAX_N]; memset(visited, false, sizeof(visited)); for (int i = 2; i <= N; ++i) { if (visited[i]) continue; visited[i] = true; for (int j = 2 * i; j <= N; j += i) { visited[j] = true; uf.unite(i, j); } } cout << uf.size(P) << endl; return 0; }