#include<stdio.h>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
 
 
using namespace std;
 
//conversion
//------------------------------------------
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}
 
//math
//-------------------------------------------
template<class T> inline T sqr(T x) {return x*x;}
 
//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef long long ll;
 
//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
 
//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
 
//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);
 
//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))
 
//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

//pair sort
bool compare_by_b(pair<LL, LL> a, pair<LL, LL> b) {
    if(a.second != b.second){
        return a.second < b.second;
    }else{
        return a.first < b.first;
    }
}

const long long MOD = 1000000007;
const long long M = 1000000007;
LL mpow(LL x, LL n){ //x^n(mod M) ←普通にpow(x,n)では溢れてしまうため，随時mod計算
    LL ans = 1;
    while(n != 0){
        if(n&1) ans = ans*x % M;
        x = x*x % M;
        n = n >> 1;
    }
    return ans;
}

vector<LL> fac(200001); //n!(mod M)
vector<LL> ifac(200001); //k!^{M-2} (mod M)
LL comb(LL a, LL b){ //aCbをmod計算
    if(a == 0 && b == 0)return 1;
    if(a < b || a < 0)return 0;
    LL tmp = ifac[a-b]* ifac[b] % M;
    return tmp * fac[a] % M;
}

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 1000000007;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res+=a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res-=a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res*=a;
  }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const {
    return pow(mod-2);
  }
  mint& operator/=(const mint a) {
    return (*this) *= a.inv();
  }
  mint operator/(const mint a) const {
    mint res(*this);
    return res/=a;
  }
};

// a^n mod を計算する
long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

mint f(int n){
    if(n==1) return 2;
    mint t = f(n/2);
    t*=t;
    if(n%2==1)t*=2;
    return t;
}

mint choose(int n, int r){
    mint x=1, y=1;
    REP(i, r){
        x *=n - i;
        y *=i+1;
    }
    return x/y;
}

void solve(long long n, long long a, long long b){
    //LL ans=modpow(2,n,MOD);
    mint ans = f(n);
    mint A=1,B=1,C=1;
    ans-=choose(n, a);
    ans -=choose(n, b);
    cout<<ans.x-1<<endl;
}

int main(){
    long long n;
    scanf("%lld",&n);
    long long a;
    scanf("%lld",&a);
    long long b;
    scanf("%lld",&b);
    solve(n, a, b);
    return 0;
}


Measured memory_bytes: 3328