#include #define VARNAME(x) #x #define show(x) cerr << #x << " = " << x << endl using namespace std; using ll = long long; using ld = long double; template vector Vec(int n, T v) { return vector(n, v); } template auto Vec(int n, Args... args) { auto val = Vec(args...); return vector(n, move(val)); } template ostream& operator<<(ostream& os, const vector& v) { os << "sz:" << v.size() << "\n["; for (const auto& p : v) { os << p << ","; } os << "]\n"; return os; } template ostream& operator<<(ostream& os, const pair& p) { os << "(" << p.first << "," << p.second << ")"; return os; } constexpr ll MOD = (ll)1e9 + 7LL; constexpr ld PI = static_cast(3.1415926535898); template constexpr T INF = numeric_limits::max() / 10; int main() { cin.tie(0); ios::sync_with_stdio(false); int N; ll M; cin >> N >> M; vector fact(N + 1); fact[0] = 1; for (int i = 1; i <= N; i++) { fact[i] = (fact[i - 1] * i) % MOD; } if (M * 2 > N) { cout << 0 << endl; return 0; } const ll n = N; N /= M; vector isprime(N + 1, true); vector p(N + 1, 0); for (int i = 2; i <= N; i++) { if (isprime[i]) { p[i] = i; for (int j = 2; i * j <= N; j++) { isprime[i * j] = false; p[i * j] = i; } } } vector d(N + 1, 0); for (int i = 2; i <= N; i++) { d[i] = d[i / p[i]] + 1; } ll ans = 0; for (int i = 1; i <= N; i++) { if (isprime[i]) { const ll num = N / i; ans += (d[i] % 2 == 0 ? 1 : MOD - 1) * (num * (num - 1) % MOD) % MOD; ans %= MOD; } } cout << (ans * fact[n - 2]) % MOD << endl; return 0; }