import sys

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 9)
INF = 1 << 60
MOD = 1000000007


def com_once(n, r, MOD):
    if n < r or n < 0 or r < 0:
        return 0
    r = min(r, n - r)
    numer = denom = 1
    for i in range(r):
        numer = numer * (n - i) % MOD
        denom = denom * (i + 1) % MOD
    return numer * pow(denom, MOD - 2, MOD) % MOD


def main():
    n, a, b = map(int, read().split())

    ans = (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD

    print(ans)
    return


if __name__ == '__main__':
    main() import sys sys read = sys.stdin.read read sys.stdin.read sys.stdin sys stdin read readline = sys.stdin.readline readline sys.stdin.readline sys.stdin sys stdin readline readlines = sys.stdin.readlines readlines sys.stdin.readlines sys.stdin sys stdin readlines sys.setrecursionlimit(10 ** 9) sys.setrecursionlimit sys setrecursionlimit 10 ** 9 10 9 INF = 1 << 60 INF 1 << 60 1 60 MOD = 1000000007 MOD 1000000007 def com_once(n, r, MOD):
    if n < r or n < 0 or r < 0:
        return 0
    r = min(r, n - r)
    numer = denom = 1
    for i in range(r):
        numer = numer * (n - i) % MOD
        denom = denom * (i + 1) % MOD
    return numer * pow(denom, MOD - 2, MOD) % MOD com_once if n < r or n < 0 or r < 0:
        return 0
     n < r or n < 0 or r < 0 n < r or n < 0 n < r n r n < 0 n 0 r < 0 r 0 return 0 0 r = min(r, n - r) r min(r, n - r) min r n - r n r numer = denom = 1 numer 1 = denom = 1 denom 1 for i in range(r):
        numer = numer * (n - i) % MOD
        denom = denom * (i + 1) % MOD
     i range(r) range r numer = numer * (n - i) % MOD numer numer * (n - i) % MOD numer * (n - i) numer n - i n i MOD denom = denom * (i + 1) % MOD denom denom * (i + 1) % MOD denom * (i + 1) denom i + 1 i 1 MOD return numer * pow(denom, MOD - 2, MOD) % MOD numer * pow(denom, MOD - 2, MOD) % MOD numer * pow(denom, MOD - 2, MOD) numer pow(denom, MOD - 2, MOD) pow denom MOD - 2 MOD 2 MOD MOD n n r r MOD MOD def main():
    n, a, b = map(int, read().split())

    ans = (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD

    print(ans)
    return main n, a, b = map(int, read().split()) n map(int, read().split()) map int read().split() ().split () read split a b ans = (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD ans (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1 pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) pow(2, n, MOD) - com_once(n, a, MOD) pow(2, n, MOD) pow 2 n MOD com_once(n, a, MOD) com_once n a MOD com_once(n, b, MOD) com_once n b MOD 1 MOD print(ans) print ans return if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def com_once(n, r, MOD):
    if n < r or n < 0 or r < 0:
        return 0
    r = min(r, n - r)
    numer = denom = 1
    for i in range(r):
        numer = numer * (n - i) % MOD
        denom = denom * (i + 1) % MOD
    return numer * pow(denom, MOD - 2, MOD) % MOD def com_once(n, r, MOD):
    if n < r or n < 0 or r < 0:
        return 0
    r = min(r, n - r)
    numer = denom = 1
    for i in range(r):
        numer = numer * (n - i) % MOD
        denom = denom * (i + 1) % MOD
    return numer * pow(denom, MOD - 2, MOD) % MOD com_once read = sys.stdin.read sys.stdin.read read readline = sys.stdin.readline sys.stdin.readline readline MOD = 1000000007 1000000007 MOD readlines = sys.stdin.readlines sys.stdin.readlines readlines INF = 1 << 60 1 << 60 INF def main():
    n, a, b = map(int, read().split())

    ans = (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD

    print(ans)
    return def main():
    n, a, b = map(int, read().split())

    ans = (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD

    print(ans)
    return main
import sys

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 9)
INF = 1 << 60
MOD = 1000000007


def com_once(n, r, MOD):
    if n < r or n < 0 or r < 0:
        return 0
    r = min(r, n - r)
    numer = denom = 1
    for i in range(r):
        numer = numer * (n - i) % MOD
        denom = denom * (i + 1) % MOD
    return numer * pow(denom, MOD - 2, MOD) % MOD


def main():
    n, a, b = map(int, read().split())

    ans = (pow(2, n, MOD) - com_once(n, a, MOD) - com_once(n, b, MOD) - 1) % MOD

    print(ans)
    return


if __name__ == '__main__':
    main()
