import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
from math import factorial
def C(n, m, P):
    c = 1
    for i in range(m):
        c *= n-i
        c %= P
    m = factorial(m)%P
    return c*pow(m, P-2, P)%P

def main():
    P = int(1e9)+7
    n, a, b = map(int, readline().split())
    print((pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P)
if __name__ == '__main__':
    main() import sys sys read = sys.stdin.buffer.read read sys.stdin.buffer.read sys.stdin.buffer sys.stdin sys stdin buffer read readline = sys.stdin.buffer.readline readline sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline readlines = sys.stdin.buffer.readlines readlines sys.stdin.buffer.readlines sys.stdin.buffer sys.stdin sys stdin buffer readlines from math import factorial def C(n, m, P):
    c = 1
    for i in range(m):
        c *= n-i
        c %= P
    m = factorial(m)%P
    return c*pow(m, P-2, P)%P C c = 1 c 1 for i in range(m):
        c *= n-i
        c %= P
     i range(m) range m c *= n-i c n-i n i c %= P c P m = factorial(m)%P m factorial(m)%P factorial(m) factorial m P return c*pow(m, P-2, P)%P c*pow(m, P-2, P)%P c*pow(m, P-2, P) c pow(m, P-2, P) pow m P-2 P 2 P P n n m m P P def main():
    P = int(1e9)+7
    n, a, b = map(int, readline().split())
    print((pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P) main P = int(1e9)+7 P int(1e9)+7 int(1e9) int 1e9 7 n, a, b = map(int, readline().split()) n map(int, readline().split()) map int readline().split() ().split () readline split a b print((pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P) print (pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P pow(2, n, P)-1-C(n, a, P)-C(n, b, P) pow(2, n, P)-1-C(n, a, P) pow(2, n, P)-1 pow(2, n, P) pow 2 n P 1 C(n, a, P) C n a P C(n, b, P) C n b P P if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main read = sys.stdin.buffer.read sys.stdin.buffer.read read def C(n, m, P):
    c = 1
    for i in range(m):
        c *= n-i
        c %= P
    m = factorial(m)%P
    return c*pow(m, P-2, P)%P def C(n, m, P):
    c = 1
    for i in range(m):
        c *= n-i
        c %= P
    m = factorial(m)%P
    return c*pow(m, P-2, P)%P C readlines = sys.stdin.buffer.readlines sys.stdin.buffer.readlines readlines readline = sys.stdin.buffer.readline sys.stdin.buffer.readline readline def main():
    P = int(1e9)+7
    n, a, b = map(int, readline().split())
    print((pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P) def main():
    P = int(1e9)+7
    n, a, b = map(int, readline().split())
    print((pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P) main
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
from math import factorial
def C(n, m, P):
    c = 1
    for i in range(m):
        c *= n-i
        c %= P
    m = factorial(m)%P
    return c*pow(m, P-2, P)%P

def main():
    P = int(1e9)+7
    n, a, b = map(int, readline().split())
    print((pow(2, n, P)-1-C(n, a, P)-C(n, b, P))%P)
if __name__ == '__main__':
    main()
