from math import factorial

 

M = 10**9 + 7

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

r = pow(2, n, M) - 1

c = 1

for i in range(b):

  c = c * (n - i) % M

  if i + 1 == a:

    r -= c * pow(factorial(a) % M, M - 2, M)

    a = b

print((r % M))

M = 10**9 + 7

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

r = pow(2, n, M) - 1

f = c = 1

for i in range(b):

  f = f * (i + 1) % M

  c = c * (n - i) % M

  if i + 1 == a:

    a = b

    r -= c * pow(f, M - 2, M)

print((r % M))

from math import factorial

M = 10**9 + 7
n, a, b = list(map(int, input().split()))
r = pow(2, n, M) - 1
c = 1
for i in range(b):
    c = c * (n - i) % M
    if i + 1 == a:
        r -= c * pow(factorial(a) % M, M - 2, M)
        a = b
print((r % M))

M = 10**9 + 7
n, a, b = list(map(int, input().split()))
r = pow(2, n, M) - 1
f = c = 1
for i in range(b):
    f = f * (i + 1) % M
    c = c * (n - i) % M
    if i + 1 == a:
        a = b
        r -= c * pow(f, M - 2, M)
print((r % M))

-from math import factorial - -c = 1 +f = c = 1 +    f = f * (i + 1) % M -        r -= c * pow(factorial(a) % M, M - 2, M) +        r -= c * pow(f, M - 2, M)