//Dragon_warrior7(IITK)
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ll long long
#define pb push_back
#define nl cout << '\n'
#define sor(x) sort(x.begin(), x.end())
#define rev(v) reverse(v.begin(), v.end())
#define lb(v, temp) lower_bound(v.begin(), v.end(), temp)
#define ub(v, temp) upper_bound(v.begin(), v.end(), temp)
#define fi first
#define se second
#define llmax 1000000000000000000
#define pll pair<ll, ll> 
#define vll vector<ll> 
#define rub cout << "\n------------------------------------\n"
#define deb(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args); }

void err(istream_iterator<string> it) {}
template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) 
{
	cout << *it << " = " << a;
	nl;
	err(++it, args...);
}
typedef  tree < int ,  null_type ,  greater<int> ,  rb_tree_tag ,  tree_order_statistics_node_update > oset;
void read(vector<ll> &v)
{
	for (int i = 0; i < v.size(); i++)
		cin >> v[i];
}
const int mod=1000000007;
ll power(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll modInverse(ll a){return power(a,mod-2);}
ll binpow(ll a, ll b, ll m) 
{a %= m;b%=(m-1);ll res = 1;while (b > 0) {if (b & 1)res = res * a % m;a = a * a % m;b >>= 1; }return res;}
ll power1(ll x, unsigned ll y, ll int p)  
{  
   ll  int res = 1;     // Initialize result  
  
    x = x % p; // Update x if it is more than or  
                // equal to p  
  
    while (y > 0)  
    {  
        // If y is odd, multiply x with result  
        if (y & 1)  
            res = (res*x) % p;  
  
        // y must be even now  
        y = y>>1; // y = y/2  
        x = (x*x) % p;  
    }  
    return res;  
}  
  
void print(vector<ll> v)
{
	for (int i = 0; i < v.size(); i++)
		cout << v[i] << " ";
}
ll n,m,a,b,c,temp,x,y;
string str;
// void modDivide(int a, int b, int m) 
// { 
//     a = a % m; 
//     int inv = modInverse(b, m); 
//     if (inv == -1) 
//       cout << "Division not defined"; 
//     else
//       cout << "Result of division is " << (inv * a) % m; 
// } 
// int gcdExtended(int a, int b, int *x, int *y) 
// { 
//     // Base Case 
//     if (a == 0) 
//     { 
//         *x = 0, *y = 1; 
//         return b; 
//     } 
  
//     int x1, y1; // To store results of recursive call 
//     int gcd = gcdExtended(b%a, a, &x1, &y1); 
  
//     // Update x and y using results of recursive 
//     // call 
//     *x = y1 - (b/a) * x1; 
//     *y = x1; 
  
//     return gcd; 
// } 
void solveforthiscase(const int & test)
{//deb(test);
cin>>n;
cin>>a>>b;
//x=n-a;
//y=n-b;
ll af=1;
for(ll i=2;i<=a;i++)
{
   af=(af*i)%mod; 
}
ll bf=1;
for(int i=2;i<=b;i++)
{
    bf=(bf*i)%mod;
}
ll ans=(power1(2,n,mod)+mod-1)%mod;
//deb(ans);
ll num=1;
for(ll i=n;i>n-a;i--)
{
    num=(num*i)%mod;
}
temp=(num*modInverse(af))%mod;
ans=(ans+mod-temp)%mod;
num=1;
for(ll i=n;i>n-b;i--)
{
    num=(num*i)%mod;
}
temp=(num*modInverse(bf))%mod;
ans=(ans+mod-temp)%mod;
cout<<ans;
return ;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int test=1;
// 	cin>>test;
    for(int i=1;i<=test;i++)
    {
        solveforthiscase(i);
    }
}

Measured memory_bytes: 256