INF = 10 ** 9
MOD = 10 ** 9 + 7
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from  math import factorial

def main():
    n,k = map(int,input().split())
    ans = 0
    if n == 1:
        print(0)
        return
    if n == 2:
        if k == 1:
            print(3)
        else:
            print(1)
        return
    if n == k:
        npk2 = factorial(n - 2)%MOD
        for i in range(1,n):
            ans += (npk2 * k * (k - 1)//2)*i%MOD
            ans %= MOD
    
    else:
        npk = factorial(n - 1) * pow(factorial(n - k - 1),MOD - 2,MOD) % MOD
        npk2 = factorial(n - 2) * pow(factorial(n - k),MOD - 2,MOD) %MOD
        for i in range(1,n):
            ans += (npk + npk2 * k * (k - 1)//2)*i%MOD
            ans %= MOD
        ans += n * npk
        ans %= MOD
    print(ans)
if __name__ == '__main__':
    main()