#include <bits/stdc++.h>
using namespace std;
// #include <bits/stdtr1c++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
 
 
// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
// #pragma GCC optimize("unroll-loops")
 
/// Typedef
typedef long long           ll;
typedef unsigned long       ul;
typedef unsigned long long  ull;
typedef vector<int>         vi;
typedef vector<vi>          vvi;
typedef vector<ll>          vll;
typedef pair<int,int>       pii;
typedef pair<ll,ll>         pll;
 
#define mt                  make_tuple
#define fbo                 find_by_order
#define ook                 order_of_key
#define UB                  upper_bound
#define LB                  lower_bound
#define pb                  push_back
#define ppb                 pop_back
#define MP                  make_pair
#define ff                  first
#define ss                  second
#define sf                  scanf
#define pf                  printf
#define loop(i, y)          for(int i=0; i<int(y); i++)
#define FOR(i, x, y)        for(int i=int(x); i<int(y); i++)
#define ROF(i, x, y)        for(int i=int(x); i>=int(y); i--)
#define all(c)              c.begin(), c.end()
#define sz(c)               int(c.size())
#define SQR(x)              ((x)*(x))
#define clr(x, y)           memset(x, y, sizeof(x))
#define si(x)               scanf("%d", &x)
#define sii(x, y)           scanf("%d %d", &x, &y)
#define siii(x, y, z)       scanf("%d %d %d", &x, &y, &z)
#define sl(x)               scanf("%lld", &x)
#define sll(x, y)           scanf("%lld %lld", &x, &y)
#define slll(x, y, z)       scanf("%lld %lld %lld", &x, &y, &z)
template <class T> inline T bigMod(T p,T e,T M){ ll ret = 1; for(; e > 0; e >>= 1){ if(e & 1) ret = (ret * p) % M; p = (p * p) % M; } return (T) ret;}
template <class T> inline T modInverse(T a,T M){return bigMod(a,M-2,M);}
template <class T> inline T gcd(T a,T b){if(b==0)return a;return gcd(b,a%b);}
template <class T> inline T lcm(T a,T b) {a=abs(a);b=abs(b); return (a/gcd(a,b))*b;}
template <class T> inline string int2String(T a){ostringstream str; str<<a; return str.str();}
template <class T> inline T string2int(string a){stringstream str(a); T b; str>>b; return b;}
/// Constants
#define MAX                 200005 
#define MOD                 1000000007
#define base                1000000007
#define eps                 1e-9
#define INF                 1<<20    // 2,305,843,009,213,693,952
#define inf                 2000000000       // 536,870,912
#define PI                  acos(-1.0)  // 3.1415926535897932
// #define INF              0x3f3f3f3f3f3f3f3f
// #define inf              0x3f3f3f3f
///string reverse example
ll comb( ll N, ll K ){
  ll X = 1; 
  ll Y = 1; 
  for( ll i = N; i > N-K; i-- ){
    X = (X*i)%MOD;
  }
  for( ll i = 1; i <= K; i++ ){
    Y = (Y*i)%MOD;
  }
  return 1LL * X * modInverse(Y,MOD*1LL)%MOD;   
}
int main(){
   ll n,a,b;
   cin>>n>>a>>b;
   ll x = bigMod(2LL,n*1LL,MOD*1LL);
   x = (x - 1 + MOD - comb(n,a) - comb(n,b) +MOD)%MOD; 
   cout<<x<<endl;
   	
}


Measured memory_bytes: 256