import sys
sys.setrecursionlimit(10**7)
input = sys.stdin.readline

mod = 10**9+7

n,a,b = map(int, input().split())

# def comb(n, k):
#     c = 1
#     for i in range(n - k + 1, n + 1):
#         c *= i
#         c %= mod
#
#     for i in range(1, k + 1):
#         c *= pow(i, mod - 2, mod)
#         c %= mod
#
#     return c

def comb(n, k):
    c = 1
    for i in range(k):
        c *= n - i
        c %= mod

    d = 1
    for i in range(1, k + 1):
        d *= i
        d %= mod

    return (c * pow(d, mod - 2, mod)) % mod

ans = pow(2, n, mod) - 1 - comb(n, a) - comb(n, b)
print(ans % mod) import sys sys sys.setrecursionlimit(10**7) sys.setrecursionlimit sys setrecursionlimit 10**7 10 7 input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline mod = 10**9+7 mod 10**9+7 10**9 10 9 7 n,a,b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b def comb(n, k):
    c = 1
    for i in range(k):
        c *= n - i
        c %= mod

    d = 1
    for i in range(1, k + 1):
        d *= i
        d %= mod

    return (c * pow(d, mod - 2, mod)) % mod comb c = 1 c 1 for i in range(k):
        c *= n - i
        c %= mod

     i range(k) range k c *= n - i c n - i n i c %= mod c mod d = 1 d 1 for i in range(1, k + 1):
        d *= i
        d %= mod

     i range(1, k + 1) range 1 k + 1 k 1 d *= i d i d %= mod d mod return (c * pow(d, mod - 2, mod)) % mod (c * pow(d, mod - 2, mod)) % mod c * pow(d, mod - 2, mod) c pow(d, mod - 2, mod) pow d mod - 2 mod 2 mod mod n n k k ans = pow(2, n, mod) - 1 - comb(n, a) - comb(n, b) ans pow(2, n, mod) - 1 - comb(n, a) - comb(n, b) pow(2, n, mod) - 1 - comb(n, a) pow(2, n, mod) - 1 pow(2, n, mod) pow 2 n mod 1 comb(n, a) comb n a comb(n, b) comb n b print(ans % mod) print ans % mod ans mod mod = 10**9+7 10**9+7 mod a,b = map(int, input().split()) map(int, input().split()) a b = map(int, input().split()) map(int, input().split()) b def comb(n, k):
    c = 1
    for i in range(k):
        c *= n - i
        c %= mod

    d = 1
    for i in range(1, k + 1):
        d *= i
        d %= mod

    return (c * pow(d, mod - 2, mod)) % mod def comb(n, k):
    c = 1
    for i in range(k):
        c *= n - i
        c %= mod

    d = 1
    for i in range(1, k + 1):
        d *= i
        d %= mod

    return (c * pow(d, mod - 2, mod)) % mod comb input = sys.stdin.readline sys.stdin.readline input n,a,b = map(int, input().split()) map(int, input().split()) n ans = pow(2, n, mod) - 1 - comb(n, a) - comb(n, b) pow(2, n, mod) - 1 - comb(n, a) - comb(n, b) ans
import sys
sys.setrecursionlimit(10**7)
input = sys.stdin.readline

mod = 10**9+7

n,a,b = map(int, input().split())

# def comb(n, k):
#     c = 1
#     for i in range(n - k + 1, n + 1):
#         c *= i
#         c %= mod
#
#     for i in range(1, k + 1):
#         c *= pow(i, mod - 2, mod)
#         c %= mod
#
#     return c

def comb(n, k):
    c = 1
    for i in range(k):
        c *= n - i
        c %= mod

    d = 1
    for i in range(1, k + 1):
        d *= i
        d %= mod

    return (c * pow(d, mod - 2, mod)) % mod

ans = pow(2, n, mod) - 1 - comb(n, a) - comb(n, b)
print(ans % mod)
