// Goods things are coming, just keep believing 
 
#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;
 
 
#define FOR(i, x, n) for(ll i = x; i < n; i++) 
#define pb push_back
#define pf push_front
#define ll long long
#define hii cout << "hii" << endl
#define okay cout << "okay" << endl
// #define hey cout << "hey" << endl
#define pii pair<int, int>
#define pll pair<ll, ll>
#define mpp make_pair
#define endl '\n'
#define ff first 
#define int long long
#define ss second
#define vi vector<int>
#define all(s) s.begin(), s.end()
#define si size()
 #define ld long double
#define INF 1000000000;
 
template <class T> ostream& operator << (ostream &os, const vector<T> &v) { for (T i : v) os << i << ' '; return os; }
template <class T> ostream& operator << (ostream &os, const set<T> &v) { for (T i : v) os << i << ' '; return os; }
template <class T, class S> ostream& operator << (ostream &os, const pair<T, S> &v) { os << v.first << ' ' << v.second; return os; }
template <class T, class S> ostream& operator << (ostream &os, const unordered_map<T, S> &v) { for (auto i : v) os << '(' << i.first << "=>" << i.second << ')' << ' '; return os; } 
 
 
 
#ifndef ONLINE_JUDGE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
    template <class Arg1> void __f(const char* name, Arg1&& arg1) { cerr << name << " : " << arg1 << endl; }
    template <class Arg1, class... Args>
    void __f(const char* names, Arg1&& arg1, Args&&... args) {
        const char* sep = strchr(names + 1, ',');
        cerr.write(names, sep - names) << " : " << arg1 << "  ";
        __f(sep + 1, args...);
    }
#else
#define trace(...) 0
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define _CRT_SECURE_NO_WARNINGS
#endif // ifndef ONLINE_JUDGE
 
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
 
 
 
const int N = 2e5 + 10;
const int LG = 20;
const int mod = 1e9 + 7;

int arr[N];

int p = mod;

int fact[N], invfact[N];
ll modRecursive(ll a, ll b, ll c) {
	if(b == 0){
		return 1;
	}

	if(b%2 ==0){

		//Even
		return modRecursive((a*a)%c,b/2,c);
	}else{
		// Odd
		return ((a%c)*(modRecursive((a*a)%c,b/2,c)))%c;
	}

}
ll  ncr(ll n, ll k, ll mod) {
    k = min(k, n - k);
    int ans = 1;
    int ans2 = 1;
    for(int i = 0; i < k; i++) {
        ans = ((ans%mod)*(n - i)%mod)%mod;
        ans2 = ((ans2 % mod) * ((i + 1)%mod))%mod;
    }
    return (ans % mod)*modRecursive(ans2, mod - 2, mod);
}
int power(int x, unsigned int y)  
{  
    int res = 1;
    x = x % p; 
  
    while (y > 0)  
    {  
        if (y & 1)  
            res = (res*x) % p;   
        y = y>>1;
        x = (x*x) % p;  
    }  
    return res;  
} 

void solve()
{
	int n, a, b;
	cin >> n >> a >> b;
	cout << (modRecursive(2, n, mod) - ncr(n, a, mod) - ncr(n, b, mod) - ncr(n, 0, mod) + mod * mod) % mod;
}

int32_t main() 
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
 
    int t;
    t = 1;
    // cin >> t;
    while(t--)
    	solve();
    return 0;
}

Measured memory_bytes: 384