#include #include using namespace std; const int MOD = 1e9 + 7; int mod_inv(int a, int m) { int m0 = m, t, q; int x0 = 0, x1 = 1; if (m == 1) return 0; while (a > 1) { q = a / m; t = m; m = a % m, a = t; t = x0; x0 = x1 - q * x0; x1 = t; } if (x1 < 0) x1 += m0; return x1; } int main() { int n; cin >> n; vector dp(n + 1, 0); for (int i = 2; i <= n; ++i) { dp[i] = (dp[i - 1] + (i * (i - 1) / 2) % MOD * mod_inv(i, MOD)) % MOD; } cout << dp[n] << endl; return 0; }