long long A,B,C,D,E,F,    I,J,K,  M,N,O,P,Q,R,S,T,U,V,  X,Y,Z;
//long long A,B,C,D,E,F,  H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z;
double dA,dB,dC,dD,dE,dF,   dI,dJ,dK,  dM,dN,dO,dP,dQ,dR,dS,dT,dU,dV,  dX,dY,dZ;
#include <string>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <string>
#include <iomanip>
#include <cmath>

//typedef pair<long long,long long> P;
//typedef pair<long long,P> P1;
//typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
//#define INF 100000000000000000//19桁
#define INF 1e18+5//19桁
#define mod 1000000007
#define fi first
#define se second
#define rep(i,x) for(long long i=0;i<x;i++)
#define repn(i,x) for(long long i=1;i<=x;i++)
#define REP(i,n,x) for(long long i=n;i<x;i++)
#define REPN(i,n,x) for(long long i=n+1;i<x;i++)
#define repn(i,x) for(long long i=1;i<=x;i++)
#define rrep(i,x) for(long long i=x-1;i>=0;i--)
#define rrepn(i,x) for(long long i=x;i>1;i--)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
#define All(x) (x).begin(),(x).end()
#define rAll(x) (x).rbegin(),(x).rend()

#define ALL(v)  (v).begin(),(v).end()
//#define MAX(a,b) if(a>b)
#define MAX(a,b) (((a)>(b))?(a):(b))
#define MIN(a,b) (((a)<(b))?(a):(b))
#define popcount __builtin_popcount

const string MINUSINF = "-";

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
void chmax(string &a, string b) {
    if (a == MINUSINF) a = b;
    else if (a.size() < b.size()) a = b;
    else if (a.size() == b.size()) {
        if (a < b) a = b;
    }
}


template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

#define pr printf
#define re return
#define CASET int ___T, case_n = 1; scanf("%d ", &___T); while (___T-- > 0)


int GCD(int a, int b) { return b ? GCD(b, a%b) : a; }

stack<long long> sta;   
queue<long long> que;
deque<long long> dque;

set <string> s_set;








long long sum,sum1,sum2,sum3,sum4;
long long flg,flg1,flg2,flg3,cnt,cnt1,cnt2,cnt3,cnt4;
long long wk,wk1,wk2,wk3,wk4;
long long ans;

double dsum,dsum1,dsum2,dsum3,dsum4;
double dcnt,dcnt1,dcnt2,dcnt3,dcnt4;
double dwk,dwk1,dwk2,dwk3,dwk4;
double dans;
double dmax,dmax1;
double dmin,dmin1;



//bool f;

long long weight[110], value[110]; // 品物の個数は 100 個なので少し余裕持たせてサイズ 110 に
//ll a[100010][3]; // a[i], b[i], c[i] をそれぞれまとめて a[i][0], a[i][1], a[i][2] にしてしまう
long long n,h[100005];
vector<long long> p, c;
int vis[200001];

vector<string> fi;
int Left[2100][2100], Right[2100][2100], Up[2100][2100], Down[2100][2100];

long long match[10] = {2,5,5,4,5,6,3,7,6};
vector<long long> box;






// modint: mod ŒvŽZ‚ð int ‚ðˆµ‚¤‚æ‚¤‚Éˆµ‚¦‚é�\‘¢‘Ì
template<ll MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};

const int MAX = 510000;
//const int MAX = 1000000001;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];
// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

// 二項係数計算
long long COM(ll n, ll k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

// mod. m での a の逆元 a^{-1} を計算する
long long modinv(long long a, long long m) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a / b;
        a -= t * b; swap(a, b);
        u -= t * v; swap(u, v);
    }
    u %= m;
    if (u < 0) u += m;
    return u;
}

using mint = Fp<1000000007>;

int main(){
	
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	long long max,max1;
	long long min,min1;
	

	sum=sum1=sum2=sum3=sum4=0;
	flg=flg1=flg2=flg3=cnt=cnt1=cnt2=cnt3=cnt4=0;
	max=max1=0;
	wk=wk1=wk2=wk3=wk4=0;
	ans=0;
	min=min1=INF;

	dsum=dsum1=dsum2=dsum3=dsum4=0;
	dcnt=dcnt1=dcnt2=dcnt3=dcnt4=0;
	dmax=dmax1=0;
	dwk=dwk1=dwk2=dwk3=dwk4=0;
	dans=0;
	dmin=dmin1=INF;

	//**************************ここからスタート******************************************
	std::cin >> N;
	//std::cin >> N >> M >> X;
	//std::cin >> N >> M >> K;
	//std::cin >> dB >> dA;
	std::cin >> A >> B;
	//std::cin >> A >> B >> C;
    //cin >> K;
	wk=1;
	mint aaa = modpow(mint(2), N)-1;
	//cout << aaa << endl;
	//re 0;
	//mint wkwk1=ma.nCk(N, A);
	//mint wkwk2=ma.nCk(N, B);
	//COMinit();
	wk1=1;
	wk2=1;
	for(ll i=0;i<A;i++){
		wk1=(N-i)%mod*wk1%mod;
		wk2=(i+1)%mod*wk2%mod;
	}
	wk1%=mod;
	wk2%=mod;
	wk1=wk1*modinv(wk2,mod)%mod;
	
	wk3=1;
	wk4=1;
	for(ll i=0;i<B;i++){
		wk3=(N-i)%mod*wk3%mod;
		wk4=(i+1)%mod*wk4%mod;
	}
	wk3%=mod;
	wk4%=mod;
	wk3=wk3*modinv(wk4,mod)%mod;

	//wk1=COM(N,A);
	//wk2=COM(N,B);
	//re 0;
	//pr("wk1=%lld\n",wk1);
	//pr("wk3=%lld\n",wk3);
	//cout << aaa << endl;
	cout << aaa-wk1-wk3 << endl;
	//pr("%lld\n",aaa-(wkwk1+wkwk2));
	re 0;

	//std::vector<long long> v(N);
	//std::vector<long long> w(N);
	//std::vector<long long> x(N);
	//std::vector<int> v(100, 0);
	//int a[26]={0};
	//vector<long long> flagment(N, 0);
	
	//v.push_back(i);
	//accumulate(vec.begin(), vec.end(), 0)
    //v.resize

    // 配列入力1
	/*
	for(long long i=0; i<N; i++){
		std::cin >> v[i];
	}
	*/
	//std::sort(v.begin(),v.end());//昇順ソート
	//std::sort(v.begin(),v.end(),std::greater<long long>());//降順ソート
	
	//cout << sum << '\n';
	
	// 配列入力1
	/*
	for(long long i=0; i<N; i++){
	
	}
	*/
	//文字列の出力
    //std::cout << s << std::endl;

	//ペア
	/*
	vector<pair<long long, long long> > p(N);
	for(long long i=0; i<N; i++){
		long long a, b;
		cin >> a >> b;
		p[i] = make_pair(a, b);
	}
	//sort(p.begin(), p.end());
	//sort(p.begin(), p.end(),greater<pair<long long,long long> >());
	*/

	//マップ
	/*
	map<long long,long long> numsx;
	map<long long,long long> numsy;
	//M.clear();
		
	for(long long i=0; i<M; i++){
		wk=w[i]%K;
		numsx[wk]++;
	}
	*/
	
	//マップ②
	/*
	map<string, int> mp;
    for(int i=0; i<n; i++){
        string s; cin>>s; mp[s]++;
    }
    int mx=-1;
    for(auto p:mp) mx=MAX(mx, p.second);
    for(auto p:mp){
        if(mx==p.second){
            cout<<p.first<<endl;
        }
    }
	*/

	//セット
	/*
	set<long long> st;

	if(st.find(v[i])==st.end()){
		st.insert(v[i]);
	}
	else{
		st.erase(v[i]);
	}
	*/

	//文字列入力
	/*
	string s,t;
	std::cin >> s;
	s=to_string(N);
	//sort(s.begin(), s.end());
	//s=to_string(i);
	for(long long i=0; i<s.length(); i++){
		
		//wk=(s[i+2]-'0')+10*(s[i+1]-'0')+100*(s[i]-'0');
		if(s[i]!='1'){
		}	
	}
	*/

	//if(ceil(sqrt(wk)==floor(sqrt(wk))))
	//do{
	//}while(next_permutation(v.begin(),v.end()));
	
	//std::cin >> N;
	//std::cin >> N >> M >> X;
	//std::cin >> N >> M >> K;
	//std::cin >> dB >> dA;
	//std::cin >> A >> B;
	//std::cin >> A >> B >> C;
    //cin >> K;

	if(1){
    	//printf("%lld",(ll)ceil(dB/dA));
    	//puts("Yes");
    	//printf("%d",st.size());
    	//文字列の出力
    	//std::cout << s << std::endl;
    	//printf("%.12f\n",ret);
    	//cout << sum << endl;
		//cout << sum << '\n';
		//cout << x[i] << " "  ;
		//cout << '\n';
		//pr("%02lld:%02lld",wk/60,wk%60);
	
	}
	else{
		//puts("No");
	}
	return 0;

	
}


Measured memory_bytes: 4352