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import java.util.Scanner;

public class Main {

static long mul(long x, long y, long p) {

long ans = 1;

while (y > 0) {

if (y%2 != 0) {

ans = ans * x % p;

}

x = x*x%p;

y /= 2;

}

return ans;

}

public static void main(String[] args) throws Exception{

Scanner sc = new Scanner(System.in);

long ans, t1, t2, t3;

long mod = 1000000007;

int N = sc.nextInt();

int R = sc.nextInt();

t1 = 1;

for (int i=1; i<=N; i++) {

t1 = t1*i%mod;

}

t2 = 1;

for (int i=1; i<=N-R; i++) {

t2 = t2*i%mod;

}

for (int i=1; i<=R; i++) {

t2 = t2*i%mod;

}

t3 = mul(t2, mod-2, mod);

t3 %= mod;

ans = t1*t3%mod;

System.out.println(ans);

}

}