using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Math;

namespace D_ABC156
{
    class MainClass
    {

        static long[] s;
        // static long D = 1000000000 + 7;

        public static void Main(string[] args)
        {
            // long D = 1000000000 + 7;
            s = Array.ConvertAll(ReadLine().Split().ToArray(), long.Parse);

            var ans = Power(2,s[0]);
            var c1 = Comb((int)s[0],(int)s[1]);
            var c2 = Comb((int)s[0],(int)s[2]);
            WriteLine(ans-c1-c2-1);
        }

        static ModInt Comb(int n, int r)
        {
            ModInt res = 1;
            for (int i = 1; i <= r; i++)
            {
                res *= n;
                res /= i;
                n--;
            }
            return res;
        }


        static List<ModInt> factorialMemo = new List<ModInt>() { 1 };
        static ModInt Factorial(int x)
        {
            for (int i = factorialMemo.Count; i <= x; i++) factorialMemo.Add(factorialMemo.Last() * i);
            return factorialMemo[x];
        }

        static ModInt Power(ModInt n, long m)
        {
            ModInt pow = n;
            ModInt res = 1;
            while (m > 0)
            {
                if ((m & 1) == 1) res *= pow;
                pow *= pow;
                m >>= 1;
            }
            return res;
        }
    }


    struct ModInt
    {
        public const int Mod = 1000000007;
        const long POSITIVIZER = ((long)Mod) << 31;
        long Data;
        public ModInt(long data) { if ((Data = data % Mod) < 0) Data += Mod; }
        public static implicit operator long(ModInt modInt) => modInt.Data;
        public static implicit operator ModInt(long val) => new ModInt(val);
        public static ModInt operator +(ModInt a, int b) => new ModInt() { Data = (a.Data + b + POSITIVIZER) % Mod };
        public static ModInt operator +(ModInt a, long b) => new ModInt(a.Data + b);
        public static ModInt operator +(ModInt a, ModInt b) { long res = a.Data + b.Data; return new ModInt() { Data = res >= Mod ? res - Mod : res }; }
        public static ModInt operator -(ModInt a, int b) => new ModInt() { Data = (a.Data - b + POSITIVIZER) % Mod };
        public static ModInt operator -(ModInt a, long b) => new ModInt(a.Data - b);
        public static ModInt operator -(ModInt a, ModInt b) { long res = a.Data - b.Data; return new ModInt() { Data = res < 0 ? res + Mod : res }; }
        public static ModInt operator *(ModInt a, int b) => new ModInt(a.Data * b);
        public static ModInt operator *(ModInt a, long b) => a * new ModInt(b);
        public static ModInt operator *(ModInt a, ModInt b) => new ModInt() { Data = a.Data * b.Data % Mod };
        public static ModInt operator /(ModInt a, ModInt b) => new ModInt() { Data = a.Data * GetInverse(b) % Mod };
        public static bool operator ==(ModInt a, ModInt b) => a.Data == b.Data;
        public static bool operator !=(ModInt a, ModInt b) => a.Data != b.Data;
        public override string ToString() => Data.ToString();
        public override bool Equals(object obj) => (ModInt)obj == this;
        public override int GetHashCode() => (int)Data;
        static long GetInverse(long a)
        {
            long div, p = Mod, x1 = 1, y1 = 0, x2 = 0, y2 = 1;
            while (true)
            {
                if (p == 1) return x2 + Mod; div = a / p; x1 -= x2 * div; y1 -= y2 * div; a %= p;
                if (a == 1) return x1 + Mod; div = p / a; x2 -= x1 * div; y2 -= y1 * div; p %= a;
            }
        }
    }

}


Measured memory_bytes: 13396