def power(x, y, p) : 
    res = 1     # Initialize result 
  
    # Update x if it is more 
    # than or equal to p 
    x = x % p  
      
    if (x == 0) : 
        return 0
  
    while (y > 0) : 
          
        # If y is odd, multiply 
        # x with result 
        if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
        y = y >> 1      # y = y/2 
        x = (x * x) % p 
          
    return res 
def ncr(n, r, p): 
    # initialize numerator 
    # and denominator 
    num = den = 1 
    for i in range(r): 
        num = (num * (n - i)) % p 
        den = (den * (i + 1)) % p 
    return (num * pow(den, p - 2, p)) % p 
n,a,b=map(int,input().split())
m=10**9+7;
ans=power(2,n,m)
ans-=ncr(n,a,m)
ans-=ncr(n,b,m)
print(ans%m-1) def power(x, y, p) : 
    res = 1     # Initialize result 
  
    # Update x if it is more 
    # than or equal to p 
    x = x % p  
      
    if (x == 0) : 
        return 0
  
    while (y > 0) : 
          
        # If y is odd, multiply 
        # x with result 
        if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
        y = y >> 1      # y = y/2 
        x = (x * x) % p 
          
    return res  power res = 1 res 1 x = x % p x x % p x p if (x == 0) : 
        return 0
  
     x == 0 x 0 return 0 0 while (y > 0) : 
          
        # If y is odd, multiply 
        # x with result 
        if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
        y = y >> 1      # y = y/2 
        x = (x * x) % p 
          
     y > 0 y 0 if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
         (y & 1) == 1 y & 1 y 1 1 res = (res * x) % p res (res * x) % p res * x res x p y = y >> 1 y y >> 1 y 1 x = (x * x) % p x (x * x) % p x * x x x p return res res x x y y p p def ncr(n, r, p): 
    # initialize numerator 
    # and denominator 
    num = den = 1 
    for i in range(r): 
        num = (num * (n - i)) % p 
        den = (den * (i + 1)) % p 
    return (num * pow(den, p - 2, p)) % p  ncr num = den = 1 num 1 = den = 1 den 1 for i in range(r): 
        num = (num * (n - i)) % p 
        den = (den * (i + 1)) % p 
     i range(r) range r num = (num * (n - i)) % p num (num * (n - i)) % p num * (n - i) num n - i n i p den = (den * (i + 1)) % p den (den * (i + 1)) % p den * (i + 1) den i + 1 i 1 p return (num * pow(den, p - 2, p)) % p (num * pow(den, p - 2, p)) % p num * pow(den, p - 2, p) num pow(den, p - 2, p) pow den p - 2 p 2 p p n n r r p p n,a,b=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b m=10**9+7 m 10**9+7 10**9 10 9 7 ans=power(2,n,m) ans power(2,n,m) power 2 n m ans-=ncr(n,a,m) ans ncr(n,a,m) ncr n a m ans-=ncr(n,b,m) ans ncr(n,b,m) ncr n b m print(ans%m-1) print ans%m-1 ans%m ans m 1 a,b=map(int,input().split()) map(int,input().split()) a b=map(int,input().split()) map(int,input().split()) b ans-=ncr(n,a,m) ncr(n,a,m) ans n,a,b=map(int,input().split()) map(int,input().split()) n def power(x, y, p) : 
    res = 1     # Initialize result 
  
    # Update x if it is more 
    # than or equal to p 
    x = x % p  
      
    if (x == 0) : 
        return 0
  
    while (y > 0) : 
          
        # If y is odd, multiply 
        # x with result 
        if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
        y = y >> 1      # y = y/2 
        x = (x * x) % p 
          
    return res  def power(x, y, p) : 
    res = 1     # Initialize result 
  
    # Update x if it is more 
    # than or equal to p 
    x = x % p  
      
    if (x == 0) : 
        return 0
  
    while (y > 0) : 
          
        # If y is odd, multiply 
        # x with result 
        if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
        y = y >> 1      # y = y/2 
        x = (x * x) % p 
          
    return res  power ans=power(2,n,m) power(2,n,m) ans def ncr(n, r, p): 
    # initialize numerator 
    # and denominator 
    num = den = 1 
    for i in range(r): 
        num = (num * (n - i)) % p 
        den = (den * (i + 1)) % p 
    return (num * pow(den, p - 2, p)) % p  def ncr(n, r, p): 
    # initialize numerator 
    # and denominator 
    num = den = 1 
    for i in range(r): 
        num = (num * (n - i)) % p 
        den = (den * (i + 1)) % p 
    return (num * pow(den, p - 2, p)) % p  ncr m=10**9+7 10**9+7 m ans-=ncr(n,b,m) ncr(n,b,m) ans
def power(x, y, p) : 
    res = 1     # Initialize result 
  
    # Update x if it is more 
    # than or equal to p 
    x = x % p  
      
    if (x == 0) : 
        return 0
  
    while (y > 0) : 
          
        # If y is odd, multiply 
        # x with result 
        if ((y & 1) == 1) : 
            res = (res * x) % p 
  
        # y must be even now 
        y = y >> 1      # y = y/2 
        x = (x * x) % p 
          
    return res 
def ncr(n, r, p): 
    # initialize numerator 
    # and denominator 
    num = den = 1 
    for i in range(r): 
        num = (num * (n - i)) % p 
        den = (den * (i + 1)) % p 
    return (num * pow(den, p - 2, p)) % p 
n,a,b=map(int,input().split())
m=10**9+7;
ans=power(2,n,m)
ans-=ncr(n,a,m)
ans-=ncr(n,b,m)
print(ans%m-1)
