def main():
    #input data
    import sys
    input = lambda:sys.stdin.readline().strip()
    
    N,A,B = map(int,input().split())
    mod=10**9+7
    #solve
    #二項係数の和=2**n
    #2**n-1-nCa-nCb
    
    def cmb(n, r, mod=10**9+7):
        c = 1
        m = 1
        r = min(n - r, r)
        for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
        return c * pow(m, mod - 2, mod) % mod
                
    ans = pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod)
    print(ans%mod)

if __name__=='__main__':
    main() def main():
    #input data
    import sys
    input = lambda:sys.stdin.readline().strip()
    
    N,A,B = map(int,input().split())
    mod=10**9+7
    #solve
    #二項係数の和=2**n
    #2**n-1-nCa-nCb
    
    def cmb(n, r, mod=10**9+7):
        c = 1
        m = 1
        r = min(n - r, r)
        for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
        return c * pow(m, mod - 2, mod) % mod
                
    ans = pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod)
    print(ans%mod) main import sys sys input = lambda:sys.stdin.readline().strip() input lambda:sys.stdin.readline().strip() sys.stdin.readline().strip() sys.stdin.readline().strip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline strip N,A,B = map(int,input().split()) N map(int,input().split()) map int input().split() ().split () input split A B mod=10**9+7 mod 10**9+7 10**9 10 9 7 def cmb(n, r, mod=10**9+7):
        c = 1
        m = 1
        r = min(n - r, r)
        for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
        return c * pow(m, mod - 2, mod) % mod
                
     cmb c = 1 c 1 m = 1 m 1 r = min(n - r, r) r min(n - r, r) min n - r n r r for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
         i range(r) range r c = c * (n - i) % mod c c * (n - i) % mod c * (n - i) c n - i n i mod m = m * (i + 1) % mod m m * (i + 1) % mod m * (i + 1) m i + 1 i 1 mod return c * pow(m, mod - 2, mod) % mod c * pow(m, mod - 2, mod) % mod c * pow(m, mod - 2, mod) c pow(m, mod - 2, mod) pow m mod - 2 mod 2 mod mod n n r r mod=10**9+7 mod 10**9+7 10**9 10 9 7 ans = pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod) ans pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod) pow(2,N,mod)-1-cmb(N,A,mod) pow(2,N,mod)-1 pow(2,N,mod) pow 2 N mod 1 cmb(N,A,mod) cmb N A mod cmb(N,B,mod) cmb N B mod print(ans%mod) print ans%mod ans mod if __name__=='__main__':
    main() __name__=='__main__' __name__ '__main__' main() main def main():
    #input data
    import sys
    input = lambda:sys.stdin.readline().strip()
    
    N,A,B = map(int,input().split())
    mod=10**9+7
    #solve
    #二項係数の和=2**n
    #2**n-1-nCa-nCb
    
    def cmb(n, r, mod=10**9+7):
        c = 1
        m = 1
        r = min(n - r, r)
        for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
        return c * pow(m, mod - 2, mod) % mod
                
    ans = pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod)
    print(ans%mod) def main():
    #input data
    import sys
    input = lambda:sys.stdin.readline().strip()
    
    N,A,B = map(int,input().split())
    mod=10**9+7
    #solve
    #二項係数の和=2**n
    #2**n-1-nCa-nCb
    
    def cmb(n, r, mod=10**9+7):
        c = 1
        m = 1
        r = min(n - r, r)
        for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
        return c * pow(m, mod - 2, mod) % mod
                
    ans = pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod)
    print(ans%mod) main
def main():
    #input data
    import sys
    input = lambda:sys.stdin.readline().strip()
    
    N,A,B = map(int,input().split())
    mod=10**9+7
    #solve
    #二項係数の和=2**n
    #2**n-1-nCa-nCb
    
    def cmb(n, r, mod=10**9+7):
        c = 1
        m = 1
        r = min(n - r, r)
        for i in range(r):
            c = c * (n - i) % mod
            m = m * (i + 1) % mod
        return c * pow(m, mod - 2, mod) % mod
                
    ans = pow(2,N,mod)-1-cmb(N,A,mod)-cmb(N,B,mod)
    print(ans%mod)

if __name__=='__main__':
    main()