def mcomb(n, k):

    a = 1

    b = 1

    for i in range(k):

        a *= n - i

        a %= 1000000007

        b *= i + 1

        b %= 1000000007

    return a * pow(b, 1000000005, 1000000007) % 1000000007





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



result = pow(2, n, 1000000007) - 1

result -= mcomb(n, a)

result + 1000000007

result %= 1000000007

result -= mcomb(n, b)

result + 1000000007

result %= 1000000007

print(result)

# 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 = list(map(int, input().split()))



m = 1000000007



result = pow(2, n, m) - 1

result += m - mcomb(n, a)

result %= m

result += m - mcomb(n, b)

result %= m

print(result)

def mcomb(n, k):
    a = 1
    b = 1
    for i in range(k):
        a *= n - i
        a %= 1000000007
        b *= i + 1
        b %= 1000000007
    return a * pow(b, 1000000005, 1000000007) % 1000000007


n, a, b = list(map(int, input().split()))
result = pow(2, n, 1000000007) - 1
result -= mcomb(n, a)
result + 1000000007
result %= 1000000007
result -= mcomb(n, b)
result + 1000000007
result %= 1000000007
print(result)

# 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 = list(map(int, input().split()))
m = 1000000007
result = pow(2, n, m) - 1
result += m - mcomb(n, a)
result %= m
result += m - mcomb(n, b)
result %= m
print(result)

+# フェルマーの小定理 -        a %= 1000000007 +        a %= m -        b %= 1000000007 -    return a * pow(b, 1000000005, 1000000007) % 1000000007 +        b %= m +    return a * pow(b, m - 2, m) % m -result = pow(2, n, 1000000007) - 1 -result -= mcomb(n, a) -result + 1000000007 -result %= 1000000007 -result -= mcomb(n, b) -result + 1000000007 -result %= 1000000007 +m = 1000000007 +result = pow(2, n, m) - 1 +result += m - mcomb(n, a) +result %= m +result += m - mcomb(n, b) +result %= m