#include "bits/stdc++.h"
using namespace std;
#define MOD 1000000007
//#define MOD 998244353
const double EPS = 1e-9;
#define INF (1LL<<60)
#define D double
#define fs first
#define sc second
#define int long long
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for(int i = (b-1);i>=(a);--i)
#define REP(i,n)  FOR(i,0,(n))
#define RREP(i,n) RFOR(i,0,(n))
#define ITR(itr,mp) for(auto itr = (mp).begin(); itr != (mp).end(); ++itr)
#define RITR(itr,mp) for(auto itr = (mp).rbegin(); itr != (mp).rend(); ++itr)
#define range(i,a,b) ((a)<=(i) && (i)<(b))
#define debug(x)  cout << #x << " = " << (x) << endl;
#define SP << " " << 
typedef pair<int,int> P;
typedef vector<int> vec;
typedef vector<vector<int>> mat;

template <std::uint_fast64_t Modulus> class modint {
  using u64 = std::uint_fast64_t;

  u64 a;

public:
  constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
  constexpr u64 val() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr bool operator==(const modint rhs) const noexcept {
    return modint(*this).val() == rhs.val();
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    a += rhs.a;
    if (a >= Modulus) {
      a -= Modulus;
    }
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (a < rhs.a) {
      a += Modulus;
    }
    a -= rhs.a;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    a = a * rhs.a % Modulus;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    u64 exp = Modulus - 2;
    while (exp) {
      if (exp % 2) {
        *this *= rhs;
      }
      rhs *= rhs;
      exp /= 2;
    }
    return *this;
  }
  constexpr bool &operator == (modint rhs) noexcept {
    return this->val() == rhs.val();
  }
  constexpr bool &operator != (modint rhs) noexcept {
    return this->val() != rhs.val();
  }
  friend constexpr ostream& operator << (ostream &os, modint<Modulus> &x) noexcept {
    return os << x.val();
  }
  friend constexpr istream& operator >> (istream &is, modint<Modulus> &x) noexcept {
    return is >> x.val();
  }
  friend constexpr modint<Modulus> modpow(const modint<Modulus> &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;
  }
};
using mint = modint<MOD>;
mint combination(int n, int r) {
  if( r * 2 > n) r = n - r;
  mint dividend = 1;
  mint divisor = 1;
  REP(i,r){
    dividend *= (n - i);
    divisor *= i + 1;
  }
  return dividend / divisor;
}

signed main(){
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.precision(20);

  int n,a,b;

  cin >> n >> a >> b;

  mint ans = 2;
  ans = modpow(ans, n);
  ans -= 1;

  mint ca = combination(n, a);
  mint cb = combination(n, b);

  ans -= ca;
  ans -= cb;

  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 256