local MOD=1000000007
local function add(a,b)return (a+b)%MOD end
local function sub(a,b)return (a-b)%MOD end
local function mul_(a,b)
	local ret=0
	while(b>0)do
		if(b%2==1)then ret=(ret+a)%MOD end
		a=(a+a)%MOD
		b=math.floor(b*.5)
	end
	return ret
end
local function mul(a,b)
	return a<b and mul_(b,a)or mul_(a,b)
end
local function pow(a,b)
	local ret=1
	while(b>0)do
		if(b%2==1)then ret=mul(ret,a)end
		a=mul(a,a)
		b=math.floor(b*.5)
	end
	return ret
end
local function inv(x)
	local a=x
	local b,u,v=MOD,1,0
	repeat
		local t=math.floor(a/b)
		a,b=b,a-t*b
		u,v=v,u-t*v
	until(b==0)
	return u%MOD
end
local function div(a,b)return mul(a,inv(b))end
local function C(n,k)
	if(n<k)then return 0 end
	local ret=1
	for i=n,n-k+1,-1 do
		ret=mul(ret,i)
	end
	for i=2,k do
		ret=div(ret,i)
	end
	return ret
end

n=io.read"*n"
a=io.read"*n"
b=io.read"*n"
print(sub(sub(sub(pow(2,n),C(n,a)),C(n,b)),1))