#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef vector<double> vd;
typedef vector<vd> vdd;

#define FOR(i,x,y) for(ll i=(ll)x; i<(ll)y; ++i)
#define REP(i,y) FOR(i, 0, y)
#define RFOR(i,x,y) for(ll i=(ll)x; i>=(ll)y; --i)
#define RREP(i,x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_print(x...) cerr << "line " << __LINE__ << " : "; debug_print_in(x);

template <typename First>
void debug_print_in(First first){
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_print_in(First first, Rest... rest){
  cerr << first << " ";
  debug_print_in(rest...);
  return;
}

void IN(void){
  return;
}

template <typename First, typename... Rest>
void IN(First& first, Rest&... rest){
  cin >> first;
  IN(rest...);
  return;
}

template <typename First>
void OUT(First first){
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest){
  cout << first << " ";
  OUT(rest...);
  return;
}

template<class t, class u> void chmax(t&a,u b){if(a<b)a=b;};
template<class t, class u> void chmin(t&a,u b){if(a>b)a=b;};
int popcount(int t){return __builtin_popcount(t);} //GCC
int popcount(ll t){return __builtin_popcountll(t);} //GCC

template <typename T>
void vec_print(vector<T> VEC){
  REP(i, VEC.size()){
    cerr << VEC[i] << " ";
  }
  cerr << endl;
};

template <typename T>
void mat_print(vector<vector<T> > MAT){
  REP(i,MAT.size()){
    REP(j,MAT[i].size()){
      cerr << MAT[i][j] << " ";
    }
    cerr << endl;
  }
};

constexpr int INF = (1<<30);
constexpr ll INFLL = 1LL<<62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9)+7);

class Modulo{
  private:
    ll MAX = MOD;
    vll fac_v, finv_v, inv_v;
  public:

    void Modulo_setting(ll MAX_){
      MAX = MAX_;

      fac_v.resize(MAX+1);
      finv_v.resize(MAX+1);
      inv_v.resize(MAX+1);

      fac_v[0] = fac_v[1] = 1;
      finv_v[0] = finv_v[1] = 1;
      inv_v[1] = 1;
      for(int i=2; i<=MAX; ++i){
        //i!
        fac_v[i] = (fac_v[i-1]*i)%MOD;
        //i^{-1}
        inv_v[i] = (MOD-(inv_v[MOD%i]*(MOD/i))%MOD)%MOD;
        //(i!)^{-1}
        finv_v[i] = (finv_v[i-1]*inv_v[i])%MOD;
      }
    };

    Modulo(ll MAX_){
      Modulo_setting(MAX_);
      return;
    };

    Modulo(void){
      Modulo_setting(MOD);
      return;
    };

    ~Modulo(void){
      return;
    };

    ll inv(ll n){
      if(n<0 || n>MAX){
        fprintf(stderr, "n range error\n");
        exit(0);
      }
      return inv_v[n];
    };

    ll fac(ll n){
      if(n<0 || n>MAX){
        fprintf(stderr, "n range error\n");
        exit(0);
      }
      return fac_v[n];
    };

    ll inv_fac(ll n){
      if(n<0 || n>MAX){
        fprintf(stderr, "n range error\n");
        exit(0);
      }
      return finv_v[n];
    };

    ll ModCom(ll n, ll k){
      if(n<k) return 0;
      if(n<0 || k<0 || n-k<0) return 0;
      return (fac_v[n]*((finv_v[k]*finv_v[n-k])%MOD))%MOD;
    };

    ll ExCom(ll n, ll k){
      if(n<k) return 0;
      if(n<0 || k<0) return 0;
      ll ans = 1;
      k = min(k, n-k);
      for(ll i=0; i<k; ++i){
        ans *= (n-i);
        ans /= (i+1);
      }
      return ans;
    };

    ll pow(ll x, ll n){
      ll res=1;
      while(n>0){
        if(n&1) res=res*x%MOD;
        x=x*x%MOD;
        n>>=1;
      }
      return res;
    };

    unordered_map<ll, ll> prime_decomposer(ll n){
      unordered_map<ll, ll> mp;
      for(ll i=2; i*i<=n; ++i){
        while(n%i==0){
          mp[i]++;
          n/=i;
        }
      }
      if(n!=1) mp[n]++;
      return mp;
    };

    ll LCM(vector<ll> vec){
      unordered_map<ll, ll> mp;
      for(ll i=0; i<vec.size(); ++i){
        unordered_map<ll, ll> mp_tmp = prime_decomposer(vec[i]);
        for(auto e : mp_tmp){
          mp[e.first] = max(mp[e.first], e.second);
        }
      }
      ll lcm=1;
      for(auto e : mp){
        lcm = (lcm*pow(e.first, e.second))%MOD;
      }
      return lcm;
    };

    ll GCM(vector<ll> vec){
      unordered_map<ll, ll> mp;
      for(ll i=0; i<vec.size(); ++i){
        unordered_map<ll, ll> mp_tmp = prime_decomposer(vec[i]);
        for(auto e : mp_tmp){
          if(mp.find(e.first)==mp.end()) mp[e.first] = e.second;
          else mp[e.first] = min(mp[e.first], e.second);
        }
      }
      ll gcm=1;
      for(auto e : mp){
        gcm = (gcm*pow(e.first, e.second))%MOD;
      }
      return gcm;
    };
};

Modulo que(1E+6);

ll n, a, b;

ll search(ll n){
  ll ans = 1;
  if(n%2==1) ans=2;
  if(n==1) return 2;
  if(n==0) return 1;
  ll tmp = search(n/2);
  tmp *= tmp;
  tmp %= MOD;
  ans *= tmp;
  return ans%MOD;
}

ll com(ll n, ll k){
  ll ans = 1;
  REP(i,k){
    ans *= (n-i);
    ans %= MOD;
  }
  ans *= que.inv_fac(k);
  return ans%MOD;
}

int main(){
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after std::cin)
  ios::sync_with_stdio(false); // cut the iostream and stdio (DON'T endl; BUT "\n";)

  IN(n,a,b);

  if(n==2){
    OUT(0);
    return 0;
  }

  ll ans1 = search(n)-1;
  debug_print(ans1);
  ll ans2 = com(n,a);
  debug_print(ans2);
  ll ans3 = com(n,b);
  debug_print(ans3);

  ll ans = ans1-ans2-ans3;
  while(ans<0) ans += MOD;
  ans %= MOD;

  OUT(ans);

  return 0;
}

Measured memory_bytes: 23680