import math
n, a, b = map(int, input().split())
MOD = 1000000007

def cmb(n, r, MOD):
    x, y = 1, 1
    for i in range(r):
        x = x * (n - i) % MOD
        y = y * (i + 1) % MOD
    return x * pow(y, MOD - 2, MOD) % MOD

N = pow(2, n, MOD) - 1
A = cmb(n, a, MOD)
B = cmb(n, b, MOD)

print((N - A - B) % MOD) import math math n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b MOD = 1000000007 MOD 1000000007 def cmb(n, r, MOD):
    x, y = 1, 1
    for i in range(r):
        x = x * (n - i) % MOD
        y = y * (i + 1) % MOD
    return x * pow(y, MOD - 2, MOD) % MOD cmb x, y = 1, 1 x 1 y 1 for i in range(r):
        x = x * (n - i) % MOD
        y = y * (i + 1) % MOD
     i range(r) range r x = x * (n - i) % MOD x x * (n - i) % MOD x * (n - i) x n - i n i MOD y = y * (i + 1) % MOD y y * (i + 1) % MOD y * (i + 1) y i + 1 i 1 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 r r MOD MOD N = pow(2, n, MOD) - 1 N pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 A = cmb(n, a, MOD) A cmb(n, a, MOD) cmb n a MOD B = cmb(n, b, MOD) B cmb(n, b, MOD) cmb n b MOD print((N - A - B) % MOD) print (N - A - B) % MOD N - A - B N - A N A B MOD a, b = map(int, input().split()) map(int, input().split()) a b = map(int, input().split()) map(int, input().split()) b MOD = 1000000007 1000000007 MOD A = cmb(n, a, MOD) cmb(n, a, MOD) A N = pow(2, n, MOD) - 1 pow(2, n, MOD) - 1 N def cmb(n, r, MOD):
    x, y = 1, 1
    for i in range(r):
        x = x * (n - i) % MOD
        y = y * (i + 1) % MOD
    return x * pow(y, MOD - 2, MOD) % MOD def cmb(n, r, MOD):
    x, y = 1, 1
    for i in range(r):
        x = x * (n - i) % MOD
        y = y * (i + 1) % MOD
    return x * pow(y, MOD - 2, MOD) % MOD cmb B = cmb(n, b, MOD) cmb(n, b, MOD) B n, a, b = map(int, input().split()) map(int, input().split()) n
import math
n, a, b = map(int, input().split())
MOD = 1000000007

def cmb(n, r, MOD):
    x, y = 1, 1
    for i in range(r):
        x = x * (n - i) % MOD
        y = y * (i + 1) % MOD
    return x * pow(y, MOD - 2, MOD) % MOD

N = pow(2, n, MOD) - 1
A = cmb(n, a, MOD)
B = cmb(n, b, MOD)

print((N - A - B) % MOD)