def ncr(n, r, p):
    num = 1
    den = 1

    for i in range(r):
        num = (num*(n-i)) % p
        den = (den*(i+1)) % p

    return (num*pow(den, p-2, p)) % p

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

m = 1000000007
print((pow(2, n, m) - 1 - ncr(n, a, m) - ncr(n, b, m)) % m) def ncr(n, r, p):
    num = 1
    den = 1

    for i in range(r):
        num = (num*(n-i)) % p
        den = (den*(i+1)) % p

    return (num*pow(den, p-2, p)) % p ncr num = 1 num 1 den = 1 den 1 for i in range(r):
        num = (num*(n-i)) % p
        den = (den*(i+1)) % p

     i range(r) range r num = (num*(n-i)) % p num (num*(n-i)) % p num*(n-i) num n-i n i p den = (den*(i+1)) % p den (den*(i+1)) % p den*(i+1) den i+1 i 1 p return (num*pow(den, p-2, p)) % p (num*pow(den, p-2, p)) % p num*pow(den, p-2, p) num pow(den, p-2, p) pow den p-2 p 2 p p n n r r p p n, a, b = list(map(int, input().split())) n list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split a b m = 1000000007 m 1000000007 print((pow(2, n, m) - 1 - ncr(n, a, m) - ncr(n, b, m)) % m) print (pow(2, n, m) - 1 - ncr(n, a, m) - ncr(n, b, m)) % m pow(2, n, m) - 1 - ncr(n, a, m) - ncr(n, b, m) pow(2, n, m) - 1 - ncr(n, a, m) pow(2, n, m) - 1 pow(2, n, m) pow 2 n m 1 ncr(n, a, m) ncr n a m ncr(n, b, m) ncr n b m m n, a, b = list(map(int, input().split())) list(map(int, input().split())) n def ncr(n, r, p):
    num = 1
    den = 1

    for i in range(r):
        num = (num*(n-i)) % p
        den = (den*(i+1)) % p

    return (num*pow(den, p-2, p)) % p def ncr(n, r, p):
    num = 1
    den = 1

    for i in range(r):
        num = (num*(n-i)) % p
        den = (den*(i+1)) % p

    return (num*pow(den, p-2, p)) % p ncr b = list(map(int, input().split())) list(map(int, input().split())) b m = 1000000007 1000000007 m a, b = list(map(int, input().split())) list(map(int, input().split())) a
def ncr(n, r, p):
    num = 1
    den = 1

    for i in range(r):
        num = (num*(n-i)) % p
        den = (den*(i+1)) % p

    return (num*pow(den, p-2, p)) % p

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

m = 1000000007
print((pow(2, n, m) - 1 - ncr(n, a, m) - ncr(n, b, m)) % m)