#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#ifdef ENABLE_DEBUG
#define dump(a) cerr<<#a<<"="<<a<<endl
#define dumparr(a,n) cerr<<#a<<"["<<n<<"]="<<a[n]<<endl
#else
#define dump(a) 
#define dumparr(a,n) 
#endif
#define FOR(i, a, b) for(ll i = a;i < b;i++)
#define For(i, a) FOR(i, 0, a)
#define REV(i, a, b) for(ll i = b-1;i >= a;i--)
#define Rev(i, a) REV(i, 0, a)
#define REP(a) For(i, a)
#define SIGN(a) (a==0?0:(a>0?1:-1))

typedef long long int ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef pair<ll, ll> pll;
typedef pair<ll,pll> ppll;
typedef vector<ll> vll;
typedef long double ld;
typedef pair<ld,ld> pdd;

const ll INF=(1LL<<50);
#if __cplusplus<201700L
ll gcd(ll a, ll b) {
  if(a < b) return gcd(b, a);
  ll r;
  while ((r=a%b)) {
    a = b;
    b = r;
  }
  return b;
}
#endif
template<class T>
bool chmax(T& a,const T& b){
  if(a<b){
    a=b;
    return true;
  }
  return false;
}
template<class T>
bool chmin(T& a,const T& b){
  if(a>b){
    a=b;
    return true;
  }
  return false;
}
template<class S,class T>
std::ostream& operator<<(std::ostream& os,pair<S,T> a){
  os << "(" << a.first << "," << a.second << ")";
  return os;
}
template<class T>
std::ostream& operator<<(std::ostream& os,vector<T> a){
  os << "[ ";
  REP(a.size()){
    os<< a[i] << " ";
  }
  os<< " ]";
  return os;
}

const long long MOD = 1000000007;
template<typename T> 
int sgn(T val){
  return (T(0)<val)-(val<T(0));
}

tuple<long long,long long,long long> egcd(long long a,long long b){
  if(a==0||b==0)return std::make_tuple(0LL,0LL,0LL);
  long long sa=sgn(a),sb=sgn(b);
  a=std::abs(a);b=std::abs(b);
  long long p=1,q=0,r=0,s=1;
  while(b>0){
    long long c=a/b;
    long long d;
    d=a;a=b;b=d%b;
    d=p;p=q;q=d-c*q;
    d=r;r=s;s=d-c*s;
  }
  return std::make_tuple(a,p*sa,r*sb);
}
long long inverse(long long a,long long m){
  static map<long long,long long> cache;
  if(cache.count(a)>0){
    return cache[a];
  }
  auto b=egcd(a,m);
  if(std::get<0>(b)!=1)return 0;
  cache[a]=(std::get<1>(b)<0)?std::get<1>(b)+m:std::get<1>(b);
  return cache[a];
}
long long factorial(long long a,long long m){
  long long ret=1;
  for (long long i = 1; i <= a; i++) {
    ret*=(i%m);
    ret%=m;
  }
  return ret;
}
long long partial_factorial(long long a,long long n,long long m){
  long long ret=1;
  for (long long i = 0; i < n; i++) {
    ret*=(a-i)%m;
    ret%=m;
  }
  return ret;
}
long long combination_prime(long long n,long long r,long long m){
  long long ret;
  long long fact_r=factorial(r,m);
  ret=inverse(fact_r,m);
  long long pfact_n=partial_factorial(n,r,m);
  ret*=pfact_n;
  ret%=m;
  return ret;
}
template<typename T>
T modpow(T a,unsigned long long b,unsigned long long MOD){
  T base=a,ans=T(1LL);
  while(b){
    if(b&1){
      ans=ans*base%MOD;
    }
    base=base*base%MOD;
    b>>=1;
  }
  return ans;
}
void solve(long long n, long long a, long long b){
  ll ans=(modpow(2LL,n,MOD)+(MOD-1))%MOD;
  ans+=(MOD-combination_prime(n,a,MOD));
  ans%=MOD;
  ans+=(MOD-combination_prime(n,b,MOD));
  ans%=MOD;
  cout<<ans<<endl;
}

int main(){
  cout<<setprecision(1000);
  cin.tie(0);
  ios::sync_with_stdio(false);
    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: 256