from functools import reduce
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline

n, a, b = map(int, read().split())
MOD = 10 ** 9 + 7


def comb_mod(n, a):
    num = reduce(lambda x, y: x * y % MOD, range(n, n - a, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, a + 1))
    return num * pow(den, MOD - 2, MOD) % MOD


ans = pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) - 1
ans %= MOD

print(ans) from functools import reduce import sys sys read = sys.stdin.buffer.read read sys.stdin.buffer.read sys.stdin.buffer sys.stdin sys stdin buffer read readline = sys.stdin.buffer.readline readline sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline n, a, b = map(int, read().split()) n map(int, read().split()) map int read().split() ().split () read split a b MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 def comb_mod(n, a):
    num = reduce(lambda x, y: x * y % MOD, range(n, n - a, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, a + 1))
    return num * pow(den, MOD - 2, MOD) % MOD comb_mod num = reduce(lambda x, y: x * y % MOD, range(n, n - a, -1)) num reduce(lambda x, y: x * y % MOD, range(n, n - a, -1)) reduce lambda x, y: x * y % MOD x * y % MOD x * y x y MOD x y range(n, n - a, -1) range n n - a n a -1 den = reduce(lambda x, y: x * y % MOD, range(1, a + 1)) den reduce(lambda x, y: x * y % MOD, range(1, a + 1)) reduce lambda x, y: x * y % MOD x * y % MOD x * y x y MOD x y range(1, a + 1) range 1 a + 1 a 1 return num * pow(den, MOD - 2, MOD) % MOD num * pow(den, MOD - 2, MOD) % MOD num * pow(den, MOD - 2, MOD) num pow(den, MOD - 2, MOD) pow den MOD - 2 MOD 2 MOD MOD n n a a ans = pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) - 1 ans pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) - 1 pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) pow(2, n, MOD) - comb_mod(n, a) pow(2, n, MOD) pow 2 n MOD comb_mod(n, a) comb_mod n a comb_mod(n, b) comb_mod n b 1 ans %= MOD ans MOD print(ans) print ans read = sys.stdin.buffer.read sys.stdin.buffer.read read def comb_mod(n, a):
    num = reduce(lambda x, y: x * y % MOD, range(n, n - a, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, a + 1))
    return num * pow(den, MOD - 2, MOD) % MOD def comb_mod(n, a):
    num = reduce(lambda x, y: x * y % MOD, range(n, n - a, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, a + 1))
    return num * pow(den, MOD - 2, MOD) % MOD comb_mod ans = pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) - 1 pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) - 1 ans a, b = map(int, read().split()) map(int, read().split()) a n, a, b = map(int, read().split()) map(int, read().split()) n readline = sys.stdin.buffer.readline sys.stdin.buffer.readline readline b = map(int, read().split()) map(int, read().split()) b ans %= MOD MOD ans MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD
from functools import reduce
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline

n, a, b = map(int, read().split())
MOD = 10 ** 9 + 7


def comb_mod(n, a):
    num = reduce(lambda x, y: x * y % MOD, range(n, n - a, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, a + 1))
    return num * pow(den, MOD - 2, MOD) % MOD


ans = pow(2, n, MOD) - comb_mod(n, a) - comb_mod(n, b) - 1
ans %= MOD

print(ans)
