def modinv(a,m):
    b, u, v = m, 1, 0
    while b:
        t = a//b
        a -= t*b
        a,b = b,a
        u -= t * v
        u,v = v,u
    u %= m
    return u

n,a,b = map(int, input().split())
MOD = 10**9+7
ncnt = pow(2,n,MOD)-1
acnt = 1
for i in range(a):
    acnt *= (n-i)
    acnt *= modinv(i+1,MOD)
    acnt %= MOD

bcnt = 1
for i in range(b):
    bcnt *= (n-i)
    bcnt *= modinv(i+1,MOD)
    bcnt %= MOD

ans = ncnt - acnt - bcnt
print(ans%MOD) def modinv(a,m):
    b, u, v = m, 1, 0
    while b:
        t = a//b
        a -= t*b
        a,b = b,a
        u -= t * v
        u,v = v,u
    u %= m
    return u modinv b, u, v = m, 1, 0 b m u 1 v 0 while b:
        t = a//b
        a -= t*b
        a,b = b,a
        u -= t * v
        u,v = v,u
     b t = a//b t a//b a b a -= t*b a t*b t b a,b = b,a a b b a u -= t * v u t * v t v u,v = v,u u v v u u %= m u m return u u a a m m n,a,b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b MOD = 10**9+7 MOD 10**9+7 10**9 10 9 7 ncnt = pow(2,n,MOD)-1 ncnt pow(2,n,MOD)-1 pow(2,n,MOD) pow 2 n MOD 1 acnt = 1 acnt 1 for i in range(a):
    acnt *= (n-i)
    acnt *= modinv(i+1,MOD)
    acnt %= MOD i range(a) range a acnt *= (n-i) acnt n-i n i acnt *= modinv(i+1,MOD) acnt modinv(i+1,MOD) modinv i+1 i 1 MOD acnt %= MOD acnt MOD bcnt = 1 bcnt 1 for i in range(b):
    bcnt *= (n-i)
    bcnt *= modinv(i+1,MOD)
    bcnt %= MOD i range(b) range b bcnt *= (n-i) bcnt n-i n i bcnt *= modinv(i+1,MOD) bcnt modinv(i+1,MOD) modinv i+1 i 1 MOD bcnt %= MOD bcnt MOD ans = ncnt - acnt - bcnt ans ncnt - acnt - bcnt ncnt - acnt ncnt acnt bcnt print(ans%MOD) print ans%MOD ans MOD acnt *= modinv(i+1,MOD) modinv(i+1,MOD) acnt b = map(int, input().split()) map(int, input().split()) b MOD = 10**9+7 10**9+7 MOD acnt *= (n-i) n-i acnt n,a,b = map(int, input().split()) map(int, input().split()) n bcnt = 1 1 bcnt ncnt = pow(2,n,MOD)-1 pow(2,n,MOD)-1 ncnt bcnt *= (n-i) n-i bcnt def modinv(a,m):
    b, u, v = m, 1, 0
    while b:
        t = a//b
        a -= t*b
        a,b = b,a
        u -= t * v
        u,v = v,u
    u %= m
    return u def modinv(a,m):
    b, u, v = m, 1, 0
    while b:
        t = a//b
        a -= t*b
        a,b = b,a
        u -= t * v
        u,v = v,u
    u %= m
    return u modinv acnt = 1 1 acnt bcnt %= MOD MOD bcnt acnt %= MOD MOD acnt ans = ncnt - acnt - bcnt ncnt - acnt - bcnt ans a,b = map(int, input().split()) map(int, input().split()) a bcnt *= modinv(i+1,MOD) modinv(i+1,MOD) bcnt
def modinv(a,m):
    b, u, v = m, 1, 0
    while b:
        t = a//b
        a -= t*b
        a,b = b,a
        u -= t * v
        u,v = v,u
    u %= m
    return u

n,a,b = map(int, input().split())
MOD = 10**9+7
ncnt = pow(2,n,MOD)-1
acnt = 1
for i in range(a):
    acnt *= (n-i)
    acnt *= modinv(i+1,MOD)
    acnt %= MOD

bcnt = 1
for i in range(b):
    bcnt *= (n-i)
    bcnt *= modinv(i+1,MOD)
    bcnt %= MOD

ans = ncnt - acnt - bcnt
print(ans%MOD)