#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
#include <bitset>
#include <stack>
#include <assert.h>
#include <unordered_set>
#include <random>


using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll INF = 1e18;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(ll i = 0; i < n; i++)













const ll table_size = 300005;
ll fact[table_size], finv[table_size], inv[table_size];

// 前処理
void make_table(ll mod) {
    fact[0] = fact[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < table_size; i++){
        fact[i] = fact[i - 1] * i % mod;
        inv[i] = mod - inv[mod % i] * (mod / i) % mod;
        finv[i] = finv[i - 1] * inv[i] % mod;
    }
}

ll comb(ll n, ll r, ll mod){
    if(n < r || n < 0 || r < 0) return 0;
    return fact[n] * (finv[r] * finv[n - r] % mod) % mod;
}

ll POW(ll n, ll m, ll p){
    ll res = 1, x = n;
    for(ll i = m; i > 0; i >>= 1){
        if(i & 1){
            res *= x;
            res %= p;
        }
        x *= x;
        x %= p;
    }
    return res;
}

template<int MOD_>
class ModInt {
private:
public:
    long long val;
    constexpr ModInt(long long v = 0) noexcept : val(v % MOD_) {
        if (val < 0) val += MOD_;
    }
    constexpr int getmod() { return MOD_; }
    constexpr ModInt operator - () const noexcept {
        return val ? MOD_ - val : 0;
    }
    constexpr ModInt operator + (const ModInt& r) const noexcept { return ModInt(*this) += r; }
    constexpr ModInt operator - (const ModInt& r) const noexcept { return ModInt(*this) -= r; }
    constexpr ModInt operator * (const ModInt& r) const noexcept { return ModInt(*this) *= r; }
    constexpr ModInt operator / (const ModInt& r) const noexcept { return ModInt(*this) /= r; }
    constexpr ModInt operator % (const ModInt& r) const noexcept { return ModInt(*this) %= r; }
    constexpr ModInt operator ^ (const ModInt& r) const noexcept { return ModInt(*this) ^= r; }
    constexpr ModInt operator & (const ModInt& r) const noexcept { return ModInt(*this) &= r; }
    constexpr ModInt operator | (const ModInt& r) const noexcept { return ModInt(*this) |= r; }
    constexpr ModInt& operator += (const ModInt& r) noexcept {
        val += r.val;
        if (val >= MOD_) val -= MOD_;
        return *this;
    }
    constexpr ModInt& operator -= (const ModInt& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD_;
        return *this;
    }
    constexpr ModInt& operator *= (const ModInt& r) noexcept {
        val = val * r.val % MOD_;
        return *this;
    }
    constexpr ModInt& operator /= (const ModInt& 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 ModInt& operator %= (const ModInt& r) noexcept {
        assert(r != 0);
        val = val % r.val;
        return *this;
    }
    constexpr ModInt& operator ^= (const ModInt& r) noexcept {
        val = (val ^ r.val) % MOD_;
        return *this;
    }
    constexpr ModInt& operator &= (const ModInt& r) noexcept {
        val = val & r.val;
        return *this;
    }
    constexpr ModInt& operator |= (const ModInt& r) noexcept {
        val = (val | r.val) % MOD_;
        return *this;
    }
    constexpr bool operator == (const ModInt& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const ModInt& r) const noexcept {
        return this->val != r.val;
    }
    constexpr bool operator < (const ModInt& r) const noexcept {
        return this->val < r.val;
    }
    constexpr bool operator > (const ModInt& r) const noexcept {
        return this->val > r.val;
    }
    constexpr bool operator <= (const ModInt& r) const noexcept {
        return this->val <= r.val;
    }
    constexpr bool operator >= (const ModInt& r) const noexcept {
        return this->val >= r.val;
    }
    constexpr bool operator && (const ModInt& r) const noexcept {
        return this->val && r.val;
    }
    constexpr bool operator || (const ModInt& r) const noexcept {
        return this->val || r.val;
    }
    constexpr ModInt& operator ++ () noexcept {
        val = (val + 1) % MOD_;
        return *this;
    }
    constexpr ModInt operator ++ (int n) noexcept {
        ModInt<MOD_> t = *this;
        val = (val + 1) % MOD_;
        return t;
    }
    constexpr ModInt& operator -- () noexcept {
        val = (val - 1 + MOD_) % MOD_;
        return *this;
    }
    constexpr ModInt operator -- (int n) noexcept {
        ModInt<MOD_> t = *this;
        val = (val - 1 + MOD_) % MOD_;
        return t;
    }
    constexpr ModInt operator ! () noexcept {
        return val? 1 : 0;
    }
    friend constexpr ostream& operator << (ostream &os, const ModInt<MOD_>& x) noexcept {
        return os << x.val;
    }
    friend constexpr istream& operator >> (istream &is, ModInt<MOD_>& x) noexcept {
        return is >> x.val;
    }
    friend constexpr ModInt<MOD_> modpow(const ModInt<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;
    }
};

int main(){
    make_table(MOD);
    
    ll n, a, b;
    cin >> n >> a >> b;
    ModInt<MOD> ans = POW(2, n, MOD) - 1;
    ModInt<MOD> t1 = 1, t2 = 1;
    REP(i, a){
        t1 *= (n - i);
    }
    REP(i, a){
        t1 /= (i + 1);
    }
    REP(i, b){
        t2 *= (n - i);
    }
    REP(i, b){
        t2 /= (i + 1);
    }
    ans -= t1 + t2;
    cout << ans << endl;
}

Measured memory_bytes: 7804