MOD=10**9+7

def powmod(a,n,m): #a^n mod m
    ans=1
    while n!=0:
        if n&1: ans=ans*a%m
        a=a*a%m
        n>>=1
    return ans%m

def fact(a,b):
    ans=1
    for i in range(a,b+1): ans=ans*i%MOD
    return ans

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

ans=powmod(2,n,MOD)-1
ta1=fact(n-a+1,n)
tb1=fact(n-b+1,n)
ta2=pow(fact(1,a),MOD-2,MOD)
tb2=pow(fact(1,b),MOD-2,MOD)
a=ta1*ta2%MOD
b=tb1*tb2%MOD
print((ans-a-b)%MOD) MOD=10**9+7 MOD 10**9+7 10**9 10 9 7 def powmod(a,n,m): #a^n mod m
    ans=1
    while n!=0:
        if n&1: ans=ans*a%m
        a=a*a%m
        n>>=1
    return ans%m powmod ans=1 ans 1 while n!=0:
        if n&1: ans=ans*a%m
        a=a*a%m
        n>>=1
     n!=0 n 0 if n&1: ans=ans*a%m
         n&1 n 1 a=a*a%m a a*a%m a*a a a m n>>=1 n 1 return ans%m ans%m ans m a a n n m m def fact(a,b):
    ans=1
    for i in range(a,b+1): ans=ans*i%MOD
    return ans fact ans=1 ans 1 for i in range(a,b+1): ans=ans*i%MOD
     i range(a,b+1) range a b+1 b 1 return ans ans a a b b n,a,b=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b ans=powmod(2,n,MOD)-1 ans powmod(2,n,MOD)-1 powmod(2,n,MOD) powmod 2 n MOD 1 ta1=fact(n-a+1,n) ta1 fact(n-a+1,n) fact n-a+1 n-a n a 1 n tb1=fact(n-b+1,n) tb1 fact(n-b+1,n) fact n-b+1 n-b n b 1 n ta2=pow(fact(1,a),MOD-2,MOD) ta2 pow(fact(1,a),MOD-2,MOD) pow fact(1,a) fact 1 a MOD-2 MOD 2 MOD tb2=pow(fact(1,b),MOD-2,MOD) tb2 pow(fact(1,b),MOD-2,MOD) pow fact(1,b) fact 1 b MOD-2 MOD 2 MOD a=ta1*ta2%MOD a ta1*ta2%MOD ta1*ta2 ta1 ta2 MOD b=tb1*tb2%MOD b tb1*tb2%MOD tb1*tb2 tb1 tb2 MOD print((ans-a-b)%MOD) print (ans-a-b)%MOD ans-a-b ans-a ans a b MOD b=map(int,input().split()) map(int,input().split()) b MOD=10**9+7 10**9+7 MOD tb1=fact(n-b+1,n) fact(n-b+1,n) tb1 ta2=pow(fact(1,a),MOD-2,MOD) pow(fact(1,a),MOD-2,MOD) ta2 ta1=fact(n-a+1,n) fact(n-a+1,n) ta1 n,a,b=map(int,input().split()) map(int,input().split()) n b=tb1*tb2%MOD tb1*tb2%MOD b a=ta1*ta2%MOD ta1*ta2%MOD a a,b=map(int,input().split()) map(int,input().split()) a ans=powmod(2,n,MOD)-1 powmod(2,n,MOD)-1 ans def powmod(a,n,m): #a^n mod m
    ans=1
    while n!=0:
        if n&1: ans=ans*a%m
        a=a*a%m
        n>>=1
    return ans%m def powmod(a,n,m): #a^n mod m
    ans=1
    while n!=0:
        if n&1: ans=ans*a%m
        a=a*a%m
        n>>=1
    return ans%m powmod def fact(a,b):
    ans=1
    for i in range(a,b+1): ans=ans*i%MOD
    return ans def fact(a,b):
    ans=1
    for i in range(a,b+1): ans=ans*i%MOD
    return ans fact tb2=pow(fact(1,b),MOD-2,MOD) pow(fact(1,b),MOD-2,MOD) tb2
MOD=10**9+7

def powmod(a,n,m): #a^n mod m
    ans=1
    while n!=0:
        if n&1: ans=ans*a%m
        a=a*a%m
        n>>=1
    return ans%m

def fact(a,b):
    ans=1
    for i in range(a,b+1): ans=ans*i%MOD
    return ans

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

ans=powmod(2,n,MOD)-1
ta1=fact(n-a+1,n)
tb1=fact(n-b+1,n)
ta2=pow(fact(1,a),MOD-2,MOD)
tb2=pow(fact(1,b),MOD-2,MOD)
a=ta1*ta2%MOD
b=tb1*tb2%MOD
print((ans-a-b)%MOD)