import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) {
        final long DIV = 1000000007;
        FastScanner sc = new FastScanner();
        long n = sc.nextLong();
        int a = sc.nextInt();
        int b = sc.nextInt();

        long[] inv = new long[200010];
        for (int i = 1; i < inv.length; i++) {
            inv[i] = modinv(i, DIV);
        }

        long[] mod10 = new long[10];
        mod10[0] = 2;
        for (int i = 1; i < mod10.length; i++) {
            long tmp = mod10[i-1];
            long tmp2 = tmp;
            for (int j = 0; j < 9; j++) {
                tmp *= tmp2;
                tmp %= DIV;
            }
            mod10[i] = tmp;
        }

        long ans = 1;
        long n2 = n;
        for (int i = 0; i < mod10.length; i++) {
            long n3 = n2 % 10;
            for (int j = 0; j < n3; j++) {
                ans *= mod10[i];
                ans %= DIV;
            }
            n2 /= 10;
        }
        ans--;

        long ansa = 1;
        for (int i = 0; i < a; i++) {
            ansa *= n-i;
            ansa %= DIV;
            ansa *= inv[i+1];
            ansa %= DIV;
        }
        ans -= ansa;
        if(ans < 0) ans += DIV;
        ans %= DIV;

        ansa = 1;
        for (int i = 0; i < b; i++) {
            ansa *= n-i;
            ansa %= DIV;
            ansa *= inv[i+1];
            ansa %= DIV;
        }
        ans -= ansa;
        if(ans < 0) ans += DIV;
        ans %= DIV;

        System.out.println(ans);

    }

    static long modinv(long a, long m){
        long b = m, u = 1, v = 0;
        while(b > 0){
            long t = a / b;
            a -= t * b;
            long tmp = a;
            a = b;
            b = tmp;
            u -= t * v;
            tmp = u;
            u = v;
            v = tmp;
        }
        u %= m;
        if (u < 0) u += m;
        return u;
    }

    private static class FastScanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;
        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            }else{
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }
        private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
        private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
        public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
        public String next() {
            if (!hasNext()) throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while(isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }
        public long nextLong() {
            if (!hasNext()) throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while(true){
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                }else if(b == -1 || !isPrintableChar(b)){
                    return minus ? -n : n;
                }else{
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }
        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
            return (int) nl;
        }
        public double nextDouble() { return Double.parseDouble(next());}
    }
}



Measured memory_bytes: 23636