# フェルマーの小定理
def mcomb(n, k):
    a = 1
    b = 1
    for i in range(k):
        a *= n - i
        a %= m
        b *= i + 1
        b %= m
    return a * pow(b, m - 2, m) % m


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

m = 1000000007

result = pow(2, n, m) - 1
result -= mcomb(n, a)
result %= m
result -= mcomb(n, b)
result %= m
print(result) def mcomb(n, k):
    a = 1
    b = 1
    for i in range(k):
        a *= n - i
        a %= m
        b *= i + 1
        b %= m
    return a * pow(b, m - 2, m) % m mcomb a = 1 a 1 b = 1 b 1 for i in range(k):
        a *= n - i
        a %= m
        b *= i + 1
        b %= m
     i range(k) range k a *= n - i a n - i n i a %= m a m b *= i + 1 b i + 1 i 1 b %= m b m return a * pow(b, m - 2, m) % m a * pow(b, m - 2, m) % m a * pow(b, m - 2, m) a pow(b, m - 2, m) pow b m - 2 m 2 m m n n k k n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b m = 1000000007 m 1000000007 result = pow(2, n, m) - 1 result pow(2, n, m) - 1 pow(2, n, m) pow 2 n m 1 result -= mcomb(n, a) result mcomb(n, a) mcomb n a result %= m result m result -= mcomb(n, b) result mcomb(n, b) mcomb n b result %= m result m print(result) print result result -= mcomb(n, a) mcomb(n, a) result a, b = map(int, input().split()) map(int, input().split()) a result %= m m result n, a, b = map(int, input().split()) map(int, input().split()) n m = 1000000007 1000000007 m result = pow(2, n, m) - 1 pow(2, n, m) - 1 result result -= mcomb(n, b) mcomb(n, b) result b = map(int, input().split()) map(int, input().split()) b result %= m m result def mcomb(n, k):
    a = 1
    b = 1
    for i in range(k):
        a *= n - i
        a %= m
        b *= i + 1
        b %= m
    return a * pow(b, m - 2, m) % m def mcomb(n, k):
    a = 1
    b = 1
    for i in range(k):
        a *= n - i
        a %= m
        b *= i + 1
        b %= m
    return a * pow(b, m - 2, m) % m mcomb
# フェルマーの小定理
def mcomb(n, k):
    a = 1
    b = 1
    for i in range(k):
        a *= n - i
        a %= m
        b *= i + 1
        b %= m
    return a * pow(b, m - 2, m) % m


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

m = 1000000007

result = pow(2, n, m) - 1
result -= mcomb(n, a)
result %= m
result -= mcomb(n, b)
result %= m
print(result)
