import math

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

MOD = int(1e9) + 7

s = pow(2, n, MOD)-1

def cbn(n, a, MOD):
    x = 1
    for i in range(a):
        x = (x * (n-i)) % MOD

    y = math.factorial(a) % MOD
    return x * pow(y, MOD-2, MOD) %MOD

s = (s- cbn(n, a, MOD)) %MOD
s = (s- cbn(n, b, MOD)) %MOD


print(s) import math math n, a, b = list(map(int, input().split())) n list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split a b MOD = int(1e9) + 7 MOD int(1e9) + 7 int(1e9) int 1e9 7 s = pow(2, n, MOD)-1 s pow(2, n, MOD)-1 pow(2, n, MOD) pow 2 n MOD 1 def cbn(n, a, MOD):
    x = 1
    for i in range(a):
        x = (x * (n-i)) % MOD

    y = math.factorial(a) % MOD
    return x * pow(y, MOD-2, MOD) %MOD cbn x = 1 x 1 for i in range(a):
        x = (x * (n-i)) % MOD

     i range(a) range a x = (x * (n-i)) % MOD x (x * (n-i)) % MOD x * (n-i) x n-i n i MOD y = math.factorial(a) % MOD y math.factorial(a) % MOD math.factorial(a) math.factorial math factorial a MOD return x * pow(y, MOD-2, MOD) %MOD x * pow(y, MOD-2, MOD) %MOD x * pow(y, MOD-2, MOD) x pow(y, MOD-2, MOD) pow y MOD-2 MOD 2 MOD MOD n n a a MOD MOD s = (s- cbn(n, a, MOD)) %MOD s (s- cbn(n, a, MOD)) %MOD s- cbn(n, a, MOD) s cbn(n, a, MOD) cbn n a MOD MOD s = (s- cbn(n, b, MOD)) %MOD s (s- cbn(n, b, MOD)) %MOD s- cbn(n, b, MOD) s cbn(n, b, MOD) cbn n b MOD MOD print(s) print s b = list(map(int, input().split())) list(map(int, input().split())) b n, a, b = list(map(int, input().split())) list(map(int, input().split())) n a, b = list(map(int, input().split())) list(map(int, input().split())) a s = pow(2, n, MOD)-1 pow(2, n, MOD)-1 s MOD = int(1e9) + 7 int(1e9) + 7 MOD s = (s- cbn(n, b, MOD)) %MOD (s- cbn(n, b, MOD)) %MOD s s = (s- cbn(n, a, MOD)) %MOD (s- cbn(n, a, MOD)) %MOD s def cbn(n, a, MOD):
    x = 1
    for i in range(a):
        x = (x * (n-i)) % MOD

    y = math.factorial(a) % MOD
    return x * pow(y, MOD-2, MOD) %MOD def cbn(n, a, MOD):
    x = 1
    for i in range(a):
        x = (x * (n-i)) % MOD

    y = math.factorial(a) % MOD
    return x * pow(y, MOD-2, MOD) %MOD cbn
import math

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

MOD = int(1e9) + 7

s = pow(2, n, MOD)-1

def cbn(n, a, MOD):
    x = 1
    for i in range(a):
        x = (x * (n-i)) % MOD

    y = math.factorial(a) % MOD
    return x * pow(y, MOD-2, MOD) %MOD

s = (s- cbn(n, a, MOD)) %MOD
s = (s- cbn(n, b, MOD)) %MOD


print(s)