import numpy as np
import scipy.sparse as sps
import scipy.misc as spm
import collections as col
import functools as func
import itertools as ite
import fractions as frac
import math as ma
from math import cos,sin,tan,sqrt
import cmath as cma
import copy as cp
import sys
import re
import bisect as bs
sys.setrecursionlimit(10**7)
EPS = sys.float_info.epsilon
PI = np.pi; EXP = np.e; INF = np.inf
MOD = 10**9 + 7

def sinput(): return sys.stdin.readline().strip()
def iinput(): return int(sinput())
def imap(): return map(int, sinput().split())
def fmap(): return map(float, sinput().split())
def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap())
def farr(): return list(fmap())
def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split()
def adj(n): return [[] for _ in range(n)]

#整数問題セット
def gcd(numbers): return func.reduce(frac.gcd, numbers)
def lcm(numbers): return func.reduce(LCM, numbers)
def inv(a): return pow(a, MOD-2, MOD) #逆元
def comb(n,r):
    ans = 1
    for i in range(r): ans *= n-i; ans *= inv(r-i); ans %= MOD
    return ans

n,a,b = imap()
ans = pow(2,n,MOD) - comb(n,a) - comb(n,b) - 1
print(ans%MOD) import numpy as np numpy import scipy.sparse as sps scipy.sparse import scipy.misc as spm scipy.misc import collections as col collections import functools as func functools import itertools as ite itertools import fractions as frac fractions import math as ma math from math import cos,sin,tan,sqrt import cmath as cma cmath import copy as cp copy import sys sys import re re import bisect as bs bisect sys.setrecursionlimit(10**7) sys.setrecursionlimit sys setrecursionlimit 10**7 10 7 EPS = sys.float_info.epsilon EPS sys.float_info.epsilon sys.float_info sys float_info epsilon PI = np.pi PI np.pi np pi EXP = np.e EXP np.e np e INF = np.inf INF np.inf np inf MOD = 10**9 + 7 MOD 10**9 + 7 10**9 10 9 7 def sinput(): return sys.stdin.readline().strip() sinput def iinput(): return int(sinput()) iinput def imap(): return map(int, sinput().split()) imap def fmap(): return map(float, sinput().split()) fmap def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap()) iarr 0 for _ in range(n) for _ in range(n) _ range(n) range n for _ in range(n) 0 if n: return [0 for _ in range(n)]
    else: return list(imap()) n n=0 n 0 def farr(): return list(fmap()) farr def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split() sarr "" for _ in range(n) for _ in range(n) _ range(n) range n for _ in range(n) "" if n: return ["" for _ in range(n)]
    else: return sinput().split() n n=0 n 0 [] for _ in range(n) for _ in range(n) _ range(n) range n for _ in range(n) [] def adj(n): return [[] for _ in range(n)]

#整数問題セット adj n n def gcd(numbers): return func.reduce(frac.gcd, numbers) gcd numbers numbers def lcm(numbers): return func.reduce(LCM, numbers) lcm numbers numbers def inv(a): return pow(a, MOD-2, MOD) #逆元 inv a a def comb(n,r):
    ans = 1
    for i in range(r): ans *= n-i; ans *= inv(r-i); ans %= MOD
    return ans comb ans = 1 ans 1 for i in range(r): ans *= n-i; ans *= inv(r-i); ans %= MOD
     i range(r) range r return ans ans n n r r n,a,b = imap() n imap() imap a b ans = pow(2,n,MOD) - comb(n,a) - comb(n,b) - 1 ans pow(2,n,MOD) - comb(n,a) - comb(n,b) - 1 pow(2,n,MOD) - comb(n,a) - comb(n,b) pow(2,n,MOD) - comb(n,a) pow(2,n,MOD) pow 2 n MOD comb(n,a) comb n a comb(n,b) comb n b 1 print(ans%MOD) print ans%MOD ans MOD def inv(a): return pow(a, MOD-2, MOD) #逆元 def inv(a): return pow(a, MOD-2, MOD) #逆元 inv b = imap() imap() b INF = np.inf np.inf INF ans = pow(2,n,MOD) - comb(n,a) - comb(n,b) - 1 pow(2,n,MOD) - comb(n,a) - comb(n,b) - 1 ans def farr(): return list(fmap()) def farr(): return list(fmap()) farr def gcd(numbers): return func.reduce(frac.gcd, numbers) def gcd(numbers): return func.reduce(frac.gcd, numbers) gcd n,a,b = imap() imap() n EPS = sys.float_info.epsilon sys.float_info.epsilon EPS def fmap(): return map(float, sinput().split()) def fmap(): return map(float, sinput().split()) fmap def iinput(): return int(sinput()) def iinput(): return int(sinput()) iinput def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap()) def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap()) iarr EXP = np.e np.e EXP def lcm(numbers): return func.reduce(LCM, numbers) def lcm(numbers): return func.reduce(LCM, numbers) lcm a,b = imap() imap() a PI = np.pi np.pi PI def imap(): return map(int, sinput().split()) def imap(): return map(int, sinput().split()) imap def comb(n,r):
    ans = 1
    for i in range(r): ans *= n-i; ans *= inv(r-i); ans %= MOD
    return ans def comb(n,r):
    ans = 1
    for i in range(r): ans *= n-i; ans *= inv(r-i); ans %= MOD
    return ans comb def sinput(): return sys.stdin.readline().strip() def sinput(): return sys.stdin.readline().strip() sinput MOD = 10**9 + 7 10**9 + 7 MOD def adj(n): return [[] for _ in range(n)]

#整数問題セット def adj(n): return [[] for _ in range(n)]

#整数問題セット adj def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split() def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split() sarr
import numpy as np
import scipy.sparse as sps
import scipy.misc as spm
import collections as col
import functools as func
import itertools as ite
import fractions as frac
import math as ma
from math import cos,sin,tan,sqrt
import cmath as cma
import copy as cp
import sys
import re
import bisect as bs
sys.setrecursionlimit(10**7)
EPS = sys.float_info.epsilon
PI = np.pi; EXP = np.e; INF = np.inf
MOD = 10**9 + 7

def sinput(): return sys.stdin.readline().strip()
def iinput(): return int(sinput())
def imap(): return map(int, sinput().split())
def fmap(): return map(float, sinput().split())
def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap())
def farr(): return list(fmap())
def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split()
def adj(n): return [[] for _ in range(n)]

#整数問題セット
def gcd(numbers): return func.reduce(frac.gcd, numbers)
def lcm(numbers): return func.reduce(LCM, numbers)
def inv(a): return pow(a, MOD-2, MOD) #逆元
def comb(n,r):
    ans = 1
    for i in range(r): ans *= n-i; ans *= inv(r-i); ans %= MOD
    return ans

n,a,b = imap()
ans = pow(2,n,MOD) - comb(n,a) - comb(n,b) - 1
print(ans%MOD)
