#include<bits/stdc++.h>
using namespace std;
//#include<boost/multiprecision/cpp_int.hpp>
//using boost::multiprecision::cpp_int;

#define int long long
#define cint cpp_int
#define endl "\n"
#define REP(i,a,n) for(int i=a;i<n;++i)
#define REPR(i,a,n) for(int i=a;i>n;--i)
#define RUP(a,b) (((a)+(b)-1)/(b))
#define ALL(v) (v).begin(),(v).end()
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define MOD 1000000007
#define INF LLONG_MAX/2
#define PI acos(-1.0)

typedef long long ll;
typedef pair<int,int> Pii;
typedef tuple<int,int,int> Tiii;
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef vector<Pii> VPii;
typedef vector<string> Vs;
typedef priority_queue<int> PQi;

template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
void vout(Vi &v){for(int i=0;i<(v).size();i++) cout<<v[i]<<" ";cout<<endl;}
void vvout(VVi &v){for(int i=0;i<(v).size();i++) vout(v[i]);}
int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return a/gcd(a,b)*b;}
int mypow(int x, int n, int m){if(n==0)return 1;if(n%2==0)return mypow(x*x%m,n/2,m);else return x*mypow(x,n-1,m)%m;}
int digit(int k,int i){string s = to_string(k);return s[s.size()-i]-'0';}
void uniq(Vi &v){sort(v.begin(),v.end()); v.erase(unique(v.begin(),v.end()),v.end());}
int ctoi(char c){if(c>='0'&&c<='9'){return c-'0';}return 0;}
int leng(int n){string s=to_string(n); return s.size();}
int lesscount(int x,Vi &a){return lower_bound(a.begin(),a.end(),x)-a.begin();} //vector aにおけるx未満の数の個数
int orlesscount(int x,Vi &a){return upper_bound(a.begin(),a.end(),x)-a.begin();} //vector aにおけるx以下の数の個数
int morecount(int x,Vi &a){return a.size()-orlesscount(x,a);} //vector aにおけるxより大きい数の個数
int ormorecount(int x,Vi &a){return a.size()-lesscount(x,a);} //vector aにおけるx以上の数の個数
int count(int x,Vi &a) {return upper_bound(ALL(a),x)-lower_bound(ALL(a),x);}
Vi accum(Vi &v){Vi ret((v).size()+1);REP(i,0,(v).size()) ret[i+1]=ret[i]+v[i];return ret;}
bool comp(Pii a,Pii b){
    if(a.second != b.second) return a.second<b.second;
    else return a.first<b.first;
}

//ModInt
struct mint { // 出力するときだけ.xをつける
 int x;
 mint(int x=0):x((x%MOD+MOD)%MOD){}
 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(int t) const {
   if (!t) return 1;
   mint a = pow(t>>1);
   a *= a;
   if (t&1) a *= *this;
   return a;
 }
 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;
 }
};
 
 

void solve(long long n, long long a, long long b){
    int A=mypow(2,n,MOD)-1;
    vector<mint> nC(min(n+1,b+1));
    REP(i,0,nC.size()){
        if(i==0) nC[i]=1;
        else{
            nC[i]=nC[i-1]*(n-i+1)/i;
        }
    }
    mint AA=A;
    mint B=nC[a]+nC[b];
//    vout(nC);
    mint ans=AA-B;
    cout<<ans.x<<endl;
} 

// Generated by 1.1.6 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
signed 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: 1792