import math



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



def mod_inv(x,mod):

    return pow(x,mod-2,mod)



def mod_inv_table(k):

    table = [-1] * (k+1)

    for i in range(1,k+1):

        table[i] = mod_inv(i,10**9+7)

    return table



def binomial(n,k,table):

    ret = 1

    for i in range(k):

        ret *= n-i

        ret *=table[i+1]

        ret %= 10**9+7

    return ret

    



tablea = mod_inv_table(a)

tableb = mod_inv_table(b)

ka = binomial(n,a,tablea)

kb = binomial(n,b,tableb)

alla = pow(2,n,10**9+7)

z = alla - ka -kb -1

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

mod = 10**9 + 7

aue,bue = 1,1

for i in range(a):

    aue = aue * (n-i) % mod

for i in range(b):

    bue = bue * (n-i) % mod

asita,bsita = 1,1

for i in range(1,a+1):

    asita = asita*i %mod

for i in range(1,b+1):

    bsita = bsita*i %mod

at = aue * pow(asita,mod-2,mod)

bt = bue * pow(bsita,mod-2,mod)



ans = (pow(2,n,mod) - 1 -at -bt)%mod

print(ans)
import math

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


def mod_inv(x, mod):
    return pow(x, mod - 2, mod)


def mod_inv_table(k):
    table = [-1] * (k + 1)
    for i in range(1, k + 1):
        table[i] = mod_inv(i, 10**9 + 7)
    return table


def binomial(n, k, table):
    ret = 1
    for i in range(k):
        ret *= n - i
        ret *= table[i + 1]
        ret %= 10**9 + 7
    return ret


tablea = mod_inv_table(a)
tableb = mod_inv_table(b)
ka = binomial(n, a, tablea)
kb = binomial(n, b, tableb)
alla = pow(2, n, 10**9 + 7)
z = alla - ka - kb - 1
print((z % (10**9 + 7)))

n, a, b = list(map(int, input().split()))
mod = 10**9 + 7
aue, bue = 1, 1
for i in range(a):
    aue = aue * (n - i) % mod
for i in range(b):
    bue = bue * (n - i) % mod
asita, bsita = 1, 1
for i in range(1, a + 1):
    asita = asita * i % mod
for i in range(1, b + 1):
    bsita = bsita * i % mod
at = aue * pow(asita, mod - 2, mod)
bt = bue * pow(bsita, mod - 2, mod)
ans = (pow(2, n, mod) - 1 - at - bt) % mod
print(ans)

-import math - - - -def mod_inv(x, mod): -    return pow(x, mod - 2, mod) - - -def mod_inv_table(k): -    table = [-1] * (k + 1) -    for i in range(1, k + 1): -        table[i] = mod_inv(i, 10**9 + 7) -    return table - - -def binomial(n, k, table): -    ret = 1 -    for i in range(k): -        ret *= n - i -        ret *= table[i + 1] -        ret %= 10**9 + 7 -    return ret - - -tablea = mod_inv_table(a) -tableb = mod_inv_table(b) -ka = binomial(n, a, tablea) -kb = binomial(n, b, tableb) -alla = pow(2, n, 10**9 + 7) -z = alla - ka - kb - 1 -print((z % (10**9 + 7))) +mod = 10**9 + 7 +aue, bue = 1, 1 +for i in range(a): +    aue = aue * (n - i) % mod +for i in range(b): +    bue = bue * (n - i) % mod +asita, bsita = 1, 1 +for i in range(1, a + 1): +    asita = asita * i % mod +for i in range(1, b + 1): +    bsita = bsita * i % mod +at = aue * pow(asita, mod - 2, mod) +bt = bue * pow(bsita, mod - 2, mod) +ans = (pow(2, n, mod) - 1 - at - bt) % mod +print(ans)