def inverse(a, mod):
    a %= mod
    p = mod
    x, y = 0, 1
    while a > 0:
        n = p // a
        p, a = a, p % a, 
        x, y = y, x - n * y
    return x % mod

def power(x, n, mod):
    ans = 1
    while n > 0:
        if n % 2 == 1:
            ans = ans * x % mod
        n //= 2
        x = x * x % mod
    return ans

n, a, b = map(int, input().split())
mod = 10 ** 9 + 7
ans = power(2, n, mod)
nCa = 1
for i in range(a):
    nCa = nCa * inverse(i + 1, mod) % mod * (n - i) % mod
nCb = 1
for i in range(b):
    nCb = nCb * inverse(i + 1, mod) % mod * (n - i) % mod
ans = (ans - nCa - nCb - 1) % mod
print(ans) def inverse(a, mod):
    a %= mod
    p = mod
    x, y = 0, 1
    while a > 0:
        n = p // a
        p, a = a, p % a, 
        x, y = y, x - n * y
    return x % mod inverse a %= mod a mod p = mod p mod x, y = 0, 1 x 0 y 1 while a > 0:
        n = p // a
        p, a = a, p % a, 
        x, y = y, x - n * y
     a > 0 a 0 n = p // a n p // a p a p, a = a, p % a, p a a p % a p a x, y = y, x - n * y x y y x - n * y x n * y n y return x % mod x % mod x mod a a mod mod def power(x, n, mod):
    ans = 1
    while n > 0:
        if n % 2 == 1:
            ans = ans * x % mod
        n //= 2
        x = x * x % mod
    return ans power ans = 1 ans 1 while n > 0:
        if n % 2 == 1:
            ans = ans * x % mod
        n //= 2
        x = x * x % mod
     n > 0 n 0 if n % 2 == 1:
            ans = ans * x % mod
         n % 2 == 1 n % 2 n 2 1 ans = ans * x % mod ans ans * x % mod ans * x ans x mod n //= 2 n 2 x = x * x % mod x x * x % mod x * x x x mod return ans ans x x n n mod mod n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b mod = 10 ** 9 + 7 mod 10 ** 9 + 7 10 ** 9 10 9 7 ans = power(2, n, mod) ans power(2, n, mod) power 2 n mod nCa = 1 nCa 1 for i in range(a):
    nCa = nCa * inverse(i + 1, mod) % mod * (n - i) % mod i range(a) range a nCa = nCa * inverse(i + 1, mod) % mod * (n - i) % mod nCa nCa * inverse(i + 1, mod) % mod * (n - i) % mod nCa * inverse(i + 1, mod) % mod * (n - i) nCa * inverse(i + 1, mod) % mod nCa * inverse(i + 1, mod) nCa inverse(i + 1, mod) inverse i + 1 i 1 mod mod n - i n i mod nCb = 1 nCb 1 for i in range(b):
    nCb = nCb * inverse(i + 1, mod) % mod * (n - i) % mod i range(b) range b nCb = nCb * inverse(i + 1, mod) % mod * (n - i) % mod nCb nCb * inverse(i + 1, mod) % mod * (n - i) % mod nCb * inverse(i + 1, mod) % mod * (n - i) nCb * inverse(i + 1, mod) % mod nCb * inverse(i + 1, mod) nCb inverse(i + 1, mod) inverse i + 1 i 1 mod mod n - i n i mod ans = (ans - nCa - nCb - 1) % mod ans (ans - nCa - nCb - 1) % mod ans - nCa - nCb - 1 ans - nCa - nCb ans - nCa ans nCa nCb 1 mod print(ans) print ans mod = 10 ** 9 + 7 10 ** 9 + 7 mod n, a, b = map(int, input().split()) map(int, input().split()) n a, b = map(int, input().split()) map(int, input().split()) a nCb = 1 1 nCb ans = power(2, n, mod) power(2, n, mod) ans nCa = nCa * inverse(i + 1, mod) % mod * (n - i) % mod nCa * inverse(i + 1, mod) % mod * (n - i) % mod nCa ans = (ans - nCa - nCb - 1) % mod (ans - nCa - nCb - 1) % mod ans def power(x, n, mod):
    ans = 1
    while n > 0:
        if n % 2 == 1:
            ans = ans * x % mod
        n //= 2
        x = x * x % mod
    return ans def power(x, n, mod):
    ans = 1
    while n > 0:
        if n % 2 == 1:
            ans = ans * x % mod
        n //= 2
        x = x * x % mod
    return ans power nCa = 1 1 nCa b = map(int, input().split()) map(int, input().split()) b def inverse(a, mod):
    a %= mod
    p = mod
    x, y = 0, 1
    while a > 0:
        n = p // a
        p, a = a, p % a, 
        x, y = y, x - n * y
    return x % mod def inverse(a, mod):
    a %= mod
    p = mod
    x, y = 0, 1
    while a > 0:
        n = p // a
        p, a = a, p % a, 
        x, y = y, x - n * y
    return x % mod inverse nCb = nCb * inverse(i + 1, mod) % mod * (n - i) % mod nCb * inverse(i + 1, mod) % mod * (n - i) % mod nCb
def inverse(a, mod):
    a %= mod
    p = mod
    x, y = 0, 1
    while a > 0:
        n = p // a
        p, a = a, p % a, 
        x, y = y, x - n * y
    return x % mod

def power(x, n, mod):
    ans = 1
    while n > 0:
        if n % 2 == 1:
            ans = ans * x % mod
        n //= 2
        x = x * x % mod
    return ans

n, a, b = map(int, input().split())
mod = 10 ** 9 + 7
ans = power(2, n, mod)
nCa = 1
for i in range(a):
    nCa = nCa * inverse(i + 1, mod) % mod * (n - i) % mod
nCb = 1
for i in range(b):
    nCb = nCb * inverse(i + 1, mod) % mod * (n - i) % mod
ans = (ans - nCa - nCb - 1) % mod
print(ans)