using System;
using System.Linq;
using System.Text.RegularExpressions;
using System.Collections.Generic;
using static program.Input;
using static program.MyMath;
using static System.Console;
using static program.Const;

namespace program
{
    static class Const
    {
        public static string alp = "abcdefghijklmnopqrstuvwxyz";
        public static string Alp = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        public const long MOD = 1000000007;
        public static int INF = int.MaxValue;
        public static long INFL = long.MaxValue;
    }
    class Program
    {
        static void Main()
        {
            SolveD();
            ReadKey();
        }
        static void SolveA()
        {
            var input = ScanIntArray();
            WriteLine(input[0] > 9 ? input[1] : input[1] + 100 * (10 - input[0]));
        }
        static void SolveB()
        {
            var input = ScanLongArray();
            var n = input[0];
            var k = input[1];
            WriteLine((int)(Math.Log(n, k) + 1));
        }
        static void SolveC()
        {
            var n = ScanInt();
            var a = ScanIntArray();
            var ave = Math.Round( a.Sum() / (double)n);

            WriteLine(a.Select(_ => (_ - ave) * (_ - ave)).Sum());
        }
        static void SolveD()
        {
            var input = ScanLongArray();
            var n = input[0];
            var a = input[1];
            var b = input[2];

            long[] comb = new long[200001];
            comb[0] = 1;
            for(long i=0; i<200000; i++)
            {
                comb[i+1] = (comb[i] * (n - i))%MOD; 
                comb[i+1] = (comb[i+1] * (i + 1).Inv()) % MOD;
            }

            var z = (ModPow(2, n) - comb[a] + MOD) % MOD;
            WriteLine((z - comb[b] - 1 + MOD) % MOD);
        }
    }

    static class Input
    {
        static public int ScanInt() { return int.Parse(Console.ReadLine()); }
        static public uint ScanUint() { return uint.Parse(Console.ReadLine()); }
        static public double ScanDouble() { return double.Parse(Console.ReadLine()); }
        static public long ScanLong() { return long.Parse(Console.ReadLine()); }
        static public ulong ScanUlong() { return ulong.Parse(Console.ReadLine()); }
        static public int[] ScanIntArray() { return Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray(); }
        static public uint[] ScanUintArray() { return Console.ReadLine().Split().Select(x => uint.Parse(x)).ToArray(); }
        static public double[] ScanDoubleArray() { return Console.ReadLine().Split().Select(x => double.Parse(x)).ToArray(); }
        static public long[] ScanLongArray() { return Console.ReadLine().Split().Select(x => long.Parse(x)).ToArray(); }
        static public ulong[] ScanUlongArray() { return Console.ReadLine().Split().Select(x => ulong.Parse(x)).ToArray(); }

        static public string ScanStr() { return Console.ReadLine(); }
        static public string[] ScanStrArray() { return ScanStr().Split(); }
        static public string RegaxReplace(this string arg1, string pattern, string replacement) { return Regex.Replace(arg1, pattern, replacement); }
        static public string Join<T>(this IEnumerable<T> source, string separator) { return string.Join(separator, source); }
        static public void Sort(this string[] array) { Array.Sort(array, StringComparer.OrdinalIgnoreCase); }
        static public void StringSort(this List<string> list) { list.Sort(StringComparer.OrdinalIgnoreCase); }
    }

    static class MyMath
    {
        static public int Floor2(this int a)
        {
            int N = 1;
            while (N < a) N *= 2;
            return N / 2;
        }
        static public long Floor2(this long a)
        {
            long N = 1;
            while (N < a) N *= 2;
            return N / 2;
        }
        static public int Ceiling2(this int a)
        {
            int N = 1;
            while (N < a) N *= 2;
            return N;
        }
        static public long Ceiling2(this long a)
        {
            long N = 1;
            while (N < a) N *= 2;
            return N;
        }
        static public long[] CumSum(this long[] a)
        {
            var res = new long[a.Length];
            long s = 0;
            for (int i = 0; i < a.Length; i++) res[i] = (s += a[i]);
            return res;
        }
        static public IEnumerable<int> PrimeFactors(this int n)
        {
            int tmp = n;
            for (int i = 2; i * i <= n; i++)
            {
                while (tmp % i == 0)
                {
                    tmp /= i;
                    yield return i;
                }
            }
            if (tmp != 1) yield return tmp;
        }
        static public IEnumerable<long> PrimeFactors(this long n)
        {
            var tmp = n;
            for (long i = 2; i * i <= n; i++)
            {
                while (tmp % i == 0)
                {
                    tmp /= i;
                    yield return i;
                }
            }
            if (tmp != 1) yield return tmp;
        }
        static public int Digit(this int n, int d) { if (d < 0) return 0; return (n % (int)Math.Pow(10, d + 1)) / (int)Math.Pow(10, d); }
        static public int Length(this int n) { if (n < 0) return 0; return (int)Math.Log10(n) + 1; }
        static public int Top(this int n) { return n.Digit(n.Length() - 1); }
        public static bool isPrime(this int p)
        {
            if (p <= 1) return false;
            for (int i = 2; i * i <= p; i++)
                if (p % i == 0) return false;
            return true;
        }
        public static bool isPrime(this long p)
        {
            if (p <= 1) return false;
            for (long i = 2; i * i <= p; i++)
                if (p % i == 0) return false;
            return true;
        }
        public static int GCD(int a, int b)
        {
            Func<int, int, int> gcd = null;
            gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
            return a > b ? gcd(a, b) : gcd(b, a);
        }
        public static long GCD(long a, long b)
        {
            Func<long, long, long> gcd = null;
            gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
            return a > b ? gcd(a, b) : gcd(b, a);
        }
        public static ulong extGCD(ulong a, ulong b, ref ulong x, ref ulong y)
        {
            if (b == 0)
            {
                x = 1;
                y = 0;
                return a;
            }
            var d = extGCD(b, a % b, ref y, ref x);
            y -= a / b * x;
            return d;
        }
        public static int LCM(int a, int b) { return a * b / GCD(a, b); }
        public static long LCM(long a, long b) { return a * b / GCD(a, b); }
        public static long Inv(this long a, long m = MOD)
        {
            long b = m, u = 1, v = 0;
            while (b != 0)
            {
                long t = a / b;
                a -= t * b;
                swap(ref a, ref b);
                u -= t * v;
                swap(ref u, ref v);
            }
            u %= m;
            if (u < 0) u += m;
            return u;
        }
        private static void swap(ref long a, ref long b)
        {
            var t = a;
            a = b;
            b = t;
        }
        public static long ModPow(long a, long n, long m = MOD)
        {
            long res = 1;
            while (n > 0)
            {
                if (n % 2 == 1) res = (res * a) % m;
                a = (a * a) % m;
                n >>= 1;
            }
            return res;
        }

    }


}


Measured memory_bytes: 14688