MOD = int(1e9 + 7)
n, k = map(int, input().split())

ans = 0
c, d = [1] * (min(n, k) + 1), [1] * (min(n, k) + 1)
for i in range(1, len(c)):
	c[i] = c[i - 1] * (k - i + 1) * pow(i, MOD - 2, MOD) % MOD
	d[i] = d[i - 1] * (n - i) * pow(i, MOD - 2, MOD) % MOD
	ans = (ans + pow(2, i - 1, MOD) * c[i] * d[i - 1] % MOD) % MOD
print(ans)