#include <bits/stdc++.h>
#include <algorithm>
#include <iostream>
#include <stack>
#include <queue>
#include <cmath>
#include <string>
#include <iterator>
#include <map>
#include <set>
#include <iomanip>
#include <vector>
#include <cstdint>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using Graph = vector<vector<int>>;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
#define rep(i, N) for(int i = 0; i < N; i++)
#define rep2(i, l, r) for (ll i = (ll)l; i < (ll)(r); i++)
#define INF 1000000000000000000
#define MAX 200001

const ll MOD = 1000000007;

template <typename T > inline string toString(const T &a) {ostringstream oss; oss << a; return oss.str();};

template<int MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) v += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr istream& operator >> (istream &is, Fp<MOD>& x) noexcept {
        return is >> x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};

using mint = Fp<MOD>;

ll RepeatSquaring(ll n,ll p, ll mod){
    if(p==0) return 1;
    if(p%2==0){
        ll t=RepeatSquaring(n,p/2,mod);
        t%=mod;
        return t*t % mod;
    }
    return n*RepeatSquaring(n,p-1,mod);
}

vector<long long> fact_inv, inv;

void init_nCk(int SIZE) {
    fact_inv.resize(SIZE + 5);
    inv.resize(SIZE + 5);
    fact_inv[0] = fact_inv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < SIZE + 5; i++) {
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        fact_inv[i] = fact_inv[i - 1] * inv[i] % MOD;
    }
}

long long nCk(ll n, ll k) {
    assert(!(n < k));
    assert(!(n < 0 || k < 0));
    long long ans = 1;
    for (int i = n; i >= n - k + 1; i--) {
        ans *= i;
        ans %= MOD;
    }
    return ans * fact_inv[k] % MOD;
}

int main(){
    init_nCk(1000000);
    ll n, a, b;
    cin >> n >> a >> b;
    ll ans = RepeatSquaring(2,n,MOD) - 1;
    ans -= nCk(n,a);
    ans -= nCk(n,b);
    while(ans < 0) ans+=MOD;
    cout << ans%MOD << endl;
}

Measured memory_bytes: 18692