import sys
from math import factorial

MOD = 10 ** 9 + 7


def main():
    # input = sys.stdin.buffer.readline
    n, a, b = map(int, input().split())
    comb_a = 1
    for i in range(a):
        comb_a *= n - i
        comb_a %= MOD
    comb_b = comb_a
    for i in range(a, b):
        comb_b *= n - i
        comb_b %= MOD
    invfact_b = pow(factorial(b), MOD - 2, MOD)
    invfact_a = invfact_b
    for i in range(b, a, -1):
        invfact_a *= i
        invfact_a %= MOD
    comb_a *= invfact_a
    comb_a %= MOD
    comb_b *= invfact_b
    comb_b %= MOD
    print((pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD)


if __name__ == "__main__":
    main() import sys sys from math import factorial MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 def main():
    # input = sys.stdin.buffer.readline
    n, a, b = map(int, input().split())
    comb_a = 1
    for i in range(a):
        comb_a *= n - i
        comb_a %= MOD
    comb_b = comb_a
    for i in range(a, b):
        comb_b *= n - i
        comb_b %= MOD
    invfact_b = pow(factorial(b), MOD - 2, MOD)
    invfact_a = invfact_b
    for i in range(b, a, -1):
        invfact_a *= i
        invfact_a %= MOD
    comb_a *= invfact_a
    comb_a %= MOD
    comb_b *= invfact_b
    comb_b %= MOD
    print((pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD) main n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b comb_a = 1 comb_a 1 for i in range(a):
        comb_a *= n - i
        comb_a %= MOD
     i range(a) range a comb_a *= n - i comb_a n - i n i comb_a %= MOD comb_a MOD comb_b = comb_a comb_b comb_a for i in range(a, b):
        comb_b *= n - i
        comb_b %= MOD
     i range(a, b) range a b comb_b *= n - i comb_b n - i n i comb_b %= MOD comb_b MOD invfact_b = pow(factorial(b), MOD - 2, MOD) invfact_b pow(factorial(b), MOD - 2, MOD) pow factorial(b) factorial b MOD - 2 MOD 2 MOD invfact_a = invfact_b invfact_a invfact_b for i in range(b, a, -1):
        invfact_a *= i
        invfact_a %= MOD
     i range(b, a, -1) range b a -1 invfact_a *= i invfact_a i invfact_a %= MOD invfact_a MOD comb_a *= invfact_a comb_a invfact_a comb_a %= MOD comb_a MOD comb_b *= invfact_b comb_b invfact_b comb_b %= MOD comb_b MOD print((pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD) print (pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD pow(2, n, MOD) - 1 - comb_a - comb_b pow(2, n, MOD) - 1 - comb_a pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 comb_a comb_b MOD if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    # input = sys.stdin.buffer.readline
    n, a, b = map(int, input().split())
    comb_a = 1
    for i in range(a):
        comb_a *= n - i
        comb_a %= MOD
    comb_b = comb_a
    for i in range(a, b):
        comb_b *= n - i
        comb_b %= MOD
    invfact_b = pow(factorial(b), MOD - 2, MOD)
    invfact_a = invfact_b
    for i in range(b, a, -1):
        invfact_a *= i
        invfact_a %= MOD
    comb_a *= invfact_a
    comb_a %= MOD
    comb_b *= invfact_b
    comb_b %= MOD
    print((pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD) def main():
    # input = sys.stdin.buffer.readline
    n, a, b = map(int, input().split())
    comb_a = 1
    for i in range(a):
        comb_a *= n - i
        comb_a %= MOD
    comb_b = comb_a
    for i in range(a, b):
        comb_b *= n - i
        comb_b %= MOD
    invfact_b = pow(factorial(b), MOD - 2, MOD)
    invfact_a = invfact_b
    for i in range(b, a, -1):
        invfact_a *= i
        invfact_a %= MOD
    comb_a *= invfact_a
    comb_a %= MOD
    comb_b *= invfact_b
    comb_b %= MOD
    print((pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD) main MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD
import sys
from math import factorial

MOD = 10 ** 9 + 7


def main():
    # input = sys.stdin.buffer.readline
    n, a, b = map(int, input().split())
    comb_a = 1
    for i in range(a):
        comb_a *= n - i
        comb_a %= MOD
    comb_b = comb_a
    for i in range(a, b):
        comb_b *= n - i
        comb_b %= MOD
    invfact_b = pow(factorial(b), MOD - 2, MOD)
    invfact_a = invfact_b
    for i in range(b, a, -1):
        invfact_a *= i
        invfact_a %= MOD
    comb_a *= invfact_a
    comb_a %= MOD
    comb_b *= invfact_b
    comb_b %= MOD
    print((pow(2, n, MOD) - 1 - comb_a - comb_b) % MOD)


if __name__ == "__main__":
    main()
