#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <unordered_map>
using namespace std;
#define n_l '\n'
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: "; cerr << to_string(__VA_ARGS__) << endl
template <typename T, size_t N> int SIZE(const T (&t)[N]){ return N; } template<typename T> int SIZE(const T &t){ return t.size(); } string to_string(const string s, int x1=0, int x2=1e9){ return '"' + ((x1 < s.size()) ? s.substr(x1, x2-x1+1) : "") + '"'; } string to_string(const char* s) { return to_string((string) s); } string to_string(const bool b) { return (b ? "true" : "false"); } string to_string(const char c){ return string({c}); } template<size_t N> string to_string(const bitset<N> &b, int x1=0, int x2=1e9){ string t = ""; for(int __iii__ = min(x1,SIZE(b)),  __jjj__ = min(x2, SIZE(b)-1); __iii__ <= __jjj__; ++__iii__){ t += b[__iii__] + '0'; } return '"' + t + '"'; } template <typename A, typename... C> string to_string(const A (&v), int x1=0, int x2=1e9, C... coords); int l_v_l_v_l = 0, t_a_b_s = 0; template <typename A, typename B> string to_string(const pair<A, B> &p) { l_v_l_v_l++; string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; l_v_l_v_l--; return res; } template <typename A, typename... C> string to_string(const A (&v), int x1, int x2, C... coords) { int rnk = rank<A>::value; string tab(t_a_b_s, ' '); string res = ""; bool first = true; if(l_v_l_v_l == 0) res += n_l; res += tab + "["; x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v)); auto l = begin(v); advance(l, x1); auto r = l; advance(r, (x2-x1) + (x2 < SIZE(v))); for (auto e = l; e != r; e = next(e)) { if (!first) { res += ", "; } first = false; l_v_l_v_l++; if(e != l){ if(rnk > 1) { res += n_l; t_a_b_s = l_v_l_v_l; }; } else{ t_a_b_s = 0; } res += to_string(*e, coords...); l_v_l_v_l--; } res += "]"; if(l_v_l_v_l == 0) res += n_l; return res; } void dbgm(){;} template<typename Heads, typename... Tails> void dbgm(Heads H, Tails... T){ cerr << to_string(H) << " | "; dbgm(T...); } 
#define dbgm(...) cerr << "[" << #__VA_ARGS__ << "]: "; dbgm(__VA_ARGS__); cerr << endl
#define run(a, b) cerr << fixed << setprecision(6) << (double) (b - a) / (double) (CLOCKS_PER_SEC) << " s" << endl;
#define ll long long
#define INF (2147483647)
#define MOD (int)(1e9 + 7) 

vector<ll> fac;

long long fast_power(long long base, long long power) {
    long long result = 1;
    while(power > 0) {

        if(power & 1) { 
            result = (result*base) % MOD;
        }
        base = (base * base) % MOD;
        power >>= 1; 
    }
    return result;
}

ll combination(ll a, ll b) {
    if ((a == b) || (b == 0)) {
        return 1;
    }
    if (a < b) return 0;
    ll ret = 1;
    for (ll i = 0; i < b; i++) {
        ret *= (a - i);
        ret %= MOD;
        ret *= fast_power(i + 1, MOD - 2);
        ret %= MOD;
    }
    return ret;
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll n, a, b;
    cin >> n >> a >> b;
    clock_t start = clock(); 
    ll total = fast_power(2, n) - 1;
    if(total < 0) {
        total += MOD;
    }
    total -= combination(n, a);
    if(total < 0) {
        total += MOD;
    }
    total -= combination(n, b);
    if(total < 0) {
        total += MOD;
    }
    cout << total % MOD << endl;
    clock_t end = clock();
    run(start, end);
    return 0;
}

































Measured memory_bytes: 256