// #include <bits/stdc++.h>
#include <iostream>
#include <map>
#include <cmath>
#include <ios>
#include <iomanip>
#include <algorithm>
#include <queue>
#include <stack>
#include <numeric>
// #include <windows.h>
using namespace std;
template<class T> using V = vector<T>;
template<class T> using VV = V<V<T>>;
template<class T> using VVV = V<VV<T>>;
template<class T1, class T2> using P = pair<T1, T2>;
using I = int;
using D = double;
using B = bool;
using C = char;
using S = string;
using LL = long long;
using LD = long double;
using ULL = unsigned long long;
using PII = P<I, I>;
using VPII = V<PII>;
using PLL = P<LL, LL>;
using VPLL = V<PLL>;
using VI = V<I>;
using VVI = VV<I>;
using VLL = V<LL>;
using VVLL = VV<LL>;
using VC = V<C>;
using VVC = VV<C>;
using VS = V<S>;
using VVS = VV<S>;
using VB = V<B>;
using VVB = VV<B>;
#define REP(type, i, n) for (type i = 0; i < (type)(n); ++i)
#define REP2(type, i, m, n) for (type i = (m); i < (type)(n); ++i)
#define REPR(type, i, n) for (type i = (n)-1; i >= 0; --i)
#define REPR2(type, i, m, n) for (type i = (n)-1; i >= (m); --i)
#define REPx(x, a) for(auto x : a)
#define ALL(a) a.begin(), a.end()
#define SORT(a) sort(ALL(a))
#define SORTR(a, type) sort(ALL(a), greater<type>())
#define SORTF(a, comp) sort(ALL(a), comp)
#define REVERSE(a) reverse(ALL(a))
#define SIZE(a, type) ((type)(a).size())
#define bit_search(bit, n) REP(LL, bit, 1LL<<(n))
#define bit_check(bit, i) ((bit>>(i)) & 1)
#define setpre(n) fixed << setprecision((n))
#define UNIQUE(a) do {SORT(a); (a).erase(unique(ALL(a)), (a).end());} while(0)
#define MAX(a) *max_element(ALL(a))
#define MIN(a) *min_element(ALL(a))
#define bisect_left(a, x) lower_bound(ALL(a), (x)) - a.begin()
#define bisect_right(a, x) upper_bound(ALL(a), (x)) - a.begin()
#define INPUT(a) REPx(&x, a) cin >> x;
#define INPUT2(a) REPx(&x, a) INPUT(x);
#define INPUTP(a) REPx(&x, a) cin >> x.first >> x.second;
#define ENDL cout << endl;

const int INF = 2e9;
// const LL INF = 9e18;
const LL MOD = 1e9+7;

template<class T> using PRIORITY_QUEUE = priority_queue< T, V<T>, greater<T> >;
template<class T> inline bool chmin(T &a, T b){if (a > b) {a = b; return true;} return false;}
template<class T> inline bool chmax(T &a, T b){if (a < b) {a = b; return true;} return false;}
template<class T> inline void debug1(V<T> A){REP(int, i, SIZE(A, int)){if (A[i] == INF) cout << "I ";else cout << A[i] << " ";}ENDL}
template<class T> inline void debug2(VV<T> A){REP(int, i, SIZE(A, int)){REP(int, j, SIZE(A[i], int)){if (A[i][j] == INF) cout << "I "; else cout << A[i][j] << " ";}ENDL}}

// modをとる整数型
const int mod = 1e9+7;
struct mint
{
  LL x;

  mint (LL _x=0): x((_x%mod+mod)%mod){}

  mint operator-() const
  {
    mint tmp(-x);
    return tmp;
  }
  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 tmp(x);
    tmp += a.x;
    return tmp;
  }
  mint operator-(const mint& a) const
  {
    mint tmp(x);
    tmp -= a.x;
    return tmp;
  }
  mint operator*(const mint& a) const
  {
    mint tmp(x);
    tmp *= a.x;
    return tmp;
  }

  mint pow(LL b) const
  {
    mint res(1), a = *this;
    while (b > 0)
    {
      if (b & 1) res *= a;
      a *= a;
      b >>= 1;
    }
    return res;
  }

  mint inv() const
  {
    return pow(mod-2);
  }
  mint& operator/=(const mint& a)
  {
    return *this *= a.inv();
  }
  mint operator/(const mint& a) const
  {
    mint tmp(x);
    tmp /= a;
    return tmp;
  }

};
istream& operator>>(istream& is, mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}

template<class T>
struct ModCalc
{
  V<mint> modfac, invmodfac;

  ModCalc(const T& limit): modfac(limit+1), invmodfac(limit+1)
  {
    setmodfactorial(limit+1);
    setinvmodfactorial(limit+1);
  }
  ModCalc(){}

  void setmodfactorial(const T& limit)
  {
    REP(T, i, limit)
    {
      if (i == 0 || i == 1) modfac[i] = 1;
      else modfac[i] = modfac[i-1] * i;
    }
  }

  void setinvmodfactorial(const T& limit)
  {
    invmodfac[limit-1] = mint(1) / modfac[limit-1];
    REPR(T, i, limit-1) invmodfac[i] = invmodfac[i+1] * (i+1);
  }

  // 1 <= k <= n <= 1e7
  mint modnCk(const T& n, const T& k)
  {
    return modfac[n] * invmodfac[k] * invmodfac[n-k];
  }

  // 1 <= n <= 1e9, 1 <= k <= 1e7
  mint modnCk2(const T& n, const T& k)
  {
    if (n < k) return 0;
    mint res = 1;
    REP(T, i, k) res = res * (n-i) / (i+1);
    return res;
  }
};

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  LL n, a, b;
  cin >> n >> a >> b;
  ModCalc<LL> mc;
  mint ans = 2;
  ans = ans.pow(n);
  ans -= mc.modnCk2(n, a) + mc.modnCk2(n, b) + 1;
  cout << ans << endl;

  return 0;
}


Measured memory_bytes: 3524