def combination(n, r, m):
    res = 1
    r = min(r, n - r)

    for i in range(r):
        res = res * (n - i) % m
        res = res * pow(i + 1, m - 2, m) % m
    return res

mod = 10**9 + 7
n, a, b = map(int, input().split())
total = pow(2, n, mod) - 1

total -= (combination(n, a, mod) + combination(n, b, mod)) % mod

print(total % mod) def combination(n, r, m):
    res = 1
    r = min(r, n - r)

    for i in range(r):
        res = res * (n - i) % m
        res = res * pow(i + 1, m - 2, m) % m
    return res combination res = 1 res 1 r = min(r, n - r) r min(r, n - r) min r n - r n r for i in range(r):
        res = res * (n - i) % m
        res = res * pow(i + 1, m - 2, m) % m
     i range(r) range r res = res * (n - i) % m res res * (n - i) % m res * (n - i) res n - i n i m res = res * pow(i + 1, m - 2, m) % m res res * pow(i + 1, m - 2, m) % m res * pow(i + 1, m - 2, m) res pow(i + 1, m - 2, m) pow i + 1 i 1 m - 2 m 2 m m return res res n n r r m m 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 total = pow(2, n, mod) - 1 total pow(2, n, mod) - 1 pow(2, n, mod) pow 2 n mod 1 total -= (combination(n, a, mod) + combination(n, b, mod)) % mod total (combination(n, a, mod) + combination(n, b, mod)) % mod combination(n, a, mod) + combination(n, b, mod) combination(n, a, mod) combination n a mod combination(n, b, mod) combination n b mod mod print(total % mod) print total % mod total mod n, a, b = map(int, input().split()) map(int, input().split()) n total -= (combination(n, a, mod) + combination(n, b, mod)) % mod (combination(n, a, mod) + combination(n, b, mod)) % mod total b = map(int, input().split()) map(int, input().split()) b a, b = map(int, input().split()) map(int, input().split()) a mod = 10**9 + 7 10**9 + 7 mod total = pow(2, n, mod) - 1 pow(2, n, mod) - 1 total def combination(n, r, m):
    res = 1
    r = min(r, n - r)

    for i in range(r):
        res = res * (n - i) % m
        res = res * pow(i + 1, m - 2, m) % m
    return res def combination(n, r, m):
    res = 1
    r = min(r, n - r)

    for i in range(r):
        res = res * (n - i) % m
        res = res * pow(i + 1, m - 2, m) % m
    return res combination
def combination(n, r, m):
    res = 1
    r = min(r, n - r)

    for i in range(r):
        res = res * (n - i) % m
        res = res * pow(i + 1, m - 2, m) % m
    return res

mod = 10**9 + 7
n, a, b = map(int, input().split())
total = pow(2, n, mod) - 1

total -= (combination(n, a, mod) + combination(n, b, mod)) % mod

print(total % mod)