#include <bits/stdc++.h>
using namespace std;
template<class T> void ckmin(T &a, T b) { a = min(a, b); }
template<class T> void ckmax(T &a, T b) { a = max(a, b); }
#define pb push_back
#define mp make_pair
#define cotu cout
#define itn int
#define Red ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define F first
#define S second
#define sz(x) (int)x.size()
#define all(x) (x).begin(), (x).end()
#define rep(i, n) for(int i = 0; i < n; ++i)
#define repr(i,n) for(int i = n - 1; i >= 0; --i)
#define Rep(i, a, n) for(int i = (a); i <=(n); ++i)
#define repst(i, n) for(auto it = n.begin(); it != n.end(); ++it)
#define Repr(i, a, n) for(int i = (n); i >= (a); --i)
typedef long long ll;

const int inf = int(1e9);
const int mod = inf + 7;
const int N = 1e6 + 555;
const double PI = acos(-1.0);
int dp[1001][1001];
int fact[1001];

void solve()
{
	int n, p;
	cin >> n >> p;
	fact[1] = 1;
	for(int i = 2; i <= n; ++i){
		fact[i] = fact[i - 1] * i;
		fact[i] %= mod;
	}
	for(int i = 1; i <= n; ++i){
		dp[i][i] = fact[i];
		for(int j = i - 1; j >= 1; --j)
		{
			dp[i][j] = (dp[i][j + 1] - dp[i - 1][j] + mod) % mod; 
		}
	}
	cout << dp[n][p] << endl;

}	
int main()
{
	Red;
	solve();
	return 0;
}