Mod = 1000000007
def f(n):
k = 1
for i in range(1,n+1):
k *= i
k %= Mod
return k
def m(x,n):
if n == 1:
return x
else:
A = m(x,n//2) %Mod
if n %2 == 0:
return (A*A)%Mod
else:
return (A*A*x)%Mod
N,K=map(int,input().split())
print((f(N) * m((f(N-K) * f(K)) % Mod,Mod-2))%Mod)