#pragma GCC optimize("Ofast")
#include <cstdio>
#include <cstdlib>
#include <string>
#include <algorithm>
#include <iostream>
#include <queue>
#include <vector>
#include <bitset>
#include <cmath>
#include <limits>
#include <iostream>
#include <map>
#include <set>
#include <tuple>
#include <iomanip>
#include <functional>

using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<int,ll> pil;
typedef pair<ll,int> pli;
typedef pair<ll,ll> pll;

template<class T,class U>constexpr bool chmin(T&a,const U b){if(a<=b)return false;a=b;return true;}
template<class T,class U>constexpr bool chmax(T&a,const U b){if(a>=b)return false;a=b;return true;}
#define bit(n,k) ( (n>>k)&1 )

//デバッグ
template<class T>
void Vout(vector<T> &V){
    cout<<"\nstart\n";
    const int sz=V.size();
    for(int i=0;i<sz;i++){
        cout<<i<<" "<<V[i]<<'\n';
    }
    cout<<"end\n"<<endl;
}

template<class T>
void VPout(vector<T> &V){
    cout<<"\nstart\n";
    const int sz=V.size();
    for(int i=0;i<sz;i++){
        cout<<i<<" "<<V[i].first<<" "<<V[i].second<<'\n';
    }
    cout<<"end\n"<<endl;
}


//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


constexpr int MAX=1<<30;
constexpr ll INF=1LL<<62;
constexpr int MOD=1e9+7;
int dx[]={1,-1,0,0},dy[]={0,0,-1,1};

//__builtin_popcount(S);
//#define int ll
//vector<vector<int>> data(3, vector<int>(4));
//vector.resize(a,vector<int>(b,-1));
//vector<vector<vector<要素の型>>> 変数名(要素数1, vector<vector<要素の型>>(要素数2, vector<要素の型>(要素数3, 初期値)));

struct ModInt{
    ll a;
    ModInt() : a(0) {}
    ModInt(ll x) {
        x%=MOD;
        if(x<0) x+=MOD;
        a=x;
    }

    ModInt operator+=(const ModInt p){
        a+=p.a;
        if( a>=MOD ) a-=MOD;
        return *this;
    }
    ModInt operator-=(const ModInt p){
        a-=p.a;
        if(a<0) a+=MOD;
        return *this;
    }
    ModInt operator*=(const ModInt p){
        a=(a*p.a)%MOD;
        return *this;
    }
    ModInt operator/=(const ModInt p){
        *this*=p.inverse();
        return *this;
    }

    ModInt operator+(const ModInt p){
        ModInt x(a);
        return x+=p;
    }
    ModInt operator-(const ModInt p){
        ModInt x(a);
        return x-=p;
    }
    ModInt operator*(const ModInt p){
        ModInt x(a);
        return x*=p;
    }
    ModInt operator/(const ModInt p){
        ModInt x(a);
        return x*=p.inverse();
    }

    ModInt operator=(ll p){
        p%=MOD;
        if(p<0) p+=MOD;
        a=p;
        return *this;
    }

    bool operator==(const ModInt p){
        return a==p.a;
    }

    bool operator!=(const ModInt p){
        return a!=p.a;
    }

    ModInt pow(ll N) const{
        ModInt ans(1),p(a);
        while(N>0){
            if(bit(N,0)){
                ans*=p;
            }
            p*=p;
            N>>=1;
        }
        return ans;
    }
    ModInt inverse() const{
        return pow(MOD-2);
    }

};

ModInt Mr(ll p){
    p%=MOD;
    if(p<0) p+=MOD;
    ModInt x(p);
    return x;
}


const int CMAX = 210000;
ModInt fac[CMAX],finv[CMAX],inv[CMAX];

void COMinit(){
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    for(int i=2;i<CMAX;i++){
        fac[i]=fac[i-1]*Mr(i);
        inv[i]=Mr(MOD)-inv[MOD%i]*Mr(MOD/i);
        finv[i]=finv[i-1]*inv[i];
    }
}

ModInt COM(int n,int k){
    if(n<k) return Mr(0);
    if(n<0 || k<0) return Mr(0);
    return fac[n]*finv[k]*finv[n-k];
}




signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr); 
    cout<<fixed<<setprecision(10);

    ll n,a,b;
    cin>>n>>a>>b;
    ModInt ans=Mr(2).pow(n)-Mr(1);
    COMinit();
    ModInt t(1);
    for(ll i=0;i<a;i++){
        t=t*Mr(n-i);
    }
    for(ll i=1;i<=a;i++){
        t=t/Mr(i);
    }
    ans-=t;
    t=1;
    for(ll i=0;i<b;i++){
        t=t*Mr(n-i);
    }
    for(ll i=1;i<=b;i++){
        t=t/Mr(i);
    }
    ans-=t;
    cout<<ans.a<<endl;
}

Measured memory_bytes: 5120