n,a,b=list(map(int,input().split()))

mod=10**9+7



def cmb(n, r):

    if n - r < r: r = n - r

    if r == 0: return 1

    if r == 1: return n



    numerator = [n - r + k + 1 for k in range(r)]

    denominator = [k + 1 for k in range(r)]



    for p in range(2,r+1):

        pivot = denominator[p - 1]

        if pivot > 1:

            offset = (n - r) % p

            for k in range(p-1,r,p):

                numerator[k - offset] /= pivot

                denominator[k] /= pivot



    result = 1

    for k in range(r):

        if numerator[k] > 1:

            result *= int(numerator[k])

            result%=mod



    return result





allp=pow(2,n,mod)-1

ans=(allp-cmb(n,a)%mod-cmb(n,b)%mod+mod)%mod

if n==2:

    ans=0



print(ans)
n,a,b=list(map(int,input().split()))

mod=10**9+7



def cmb(n, r,mod):

    if n - r < r: r = n - r

    if r == 0: return 1

    if r == 1: return n



    #X//Y

    X=1

    Y=1

    for i in range(r):

        X*=(n-i)

        X%=mod

        Y*=(i+1)

        Y%=mod

        

    inv=pow(Y,mod-2,mod)

    return (X*inv)%mod

        

        





allp=pow(2,n,mod)-1

ans=(allp-cmb(n,a,mod)-cmb(n,b,mod))%mod

if n==2:

    ans=0



print(ans)
n, a, b = list(map(int, input().split()))
mod = 10**9 + 7


def cmb(n, r):
    if n - r < r:
        r = n - r
    if r == 0:
        return 1
    if r == 1:
        return n
    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]
    for p in range(2, r + 1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p - 1, r, p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot
    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])
            result %= mod
    return result


allp = pow(2, n, mod) - 1
ans = (allp - cmb(n, a) % mod - cmb(n, b) % mod + mod) % mod
if n == 2:
    ans = 0
print(ans)

n, a, b = list(map(int, input().split()))
mod = 10**9 + 7


def cmb(n, r, mod):
    if n - r < r:
        r = n - r
    if r == 0:
        return 1
    if r == 1:
        return n
    # X//Y
    X = 1
    Y = 1
    for i in range(r):
        X *= n - i
        X %= mod
        Y *= i + 1
        Y %= mod
    inv = pow(Y, mod - 2, mod)
    return (X * inv) % mod


allp = pow(2, n, mod) - 1
ans = (allp - cmb(n, a, mod) - cmb(n, b, mod)) % mod
if n == 2:
    ans = 0
print(ans)

-def cmb(n, r): +def cmb(n, r, mod): -    numerator = [n - r + k + 1 for k in range(r)] -    denominator = [k + 1 for k in range(r)] -    for p in range(2, r + 1): -        pivot = denominator[p - 1] -        if pivot > 1: -            offset = (n - r) % p -            for k in range(p - 1, r, p): -                numerator[k - offset] /= pivot -                denominator[k] /= pivot -    result = 1 -    for k in range(r): -        if numerator[k] > 1: -            result *= int(numerator[k]) -            result %= mod -    return result +    # X//Y +    X = 1 +    Y = 1 +    for i in range(r): +        X *= n - i +        X %= mod +        Y *= i + 1 +        Y %= mod +    inv = pow(Y, mod - 2, mod) +    return (X * inv) % mod -ans = (allp - cmb(n, a) % mod - cmb(n, b) % mod + mod) % mod +ans = (allp - cmb(n, a, mod) - cmb(n, b, mod)) % mod