import math


n,a,b=map(int,input().split())
mod=10**9+7

c1=1
c2=1

for i in range(n-a+1,n+1):
    c1*=i
    c1%=mod
for j in range(1,a+1):
    c1*=pow(j,mod-2,mod)
    c1%=mod
    
for i in range(n-b+1,n+1):
    c2*=i
    c2%=mod
for j in range(1,b+1):
    c2*=pow(j,mod-2,mod)
    c2%=mod

ans=pow(2,n,mod)-1

print((ans-c1-c2)%mod) import math math 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 c1=1 c1 1 c2=1 c2 1 for i in range(n-a+1,n+1):
    c1*=i
    c1%=mod i range(n-a+1,n+1) range n-a+1 n-a n a 1 n+1 n 1 c1*=i c1 i c1%=mod c1 mod for j in range(1,a+1):
    c1*=pow(j,mod-2,mod)
    c1%=mod
     j range(1,a+1) range 1 a+1 a 1 c1*=pow(j,mod-2,mod) c1 pow(j,mod-2,mod) pow j mod-2 mod 2 mod c1%=mod c1 mod for i in range(n-b+1,n+1):
    c2*=i
    c2%=mod i range(n-b+1,n+1) range n-b+1 n-b n b 1 n+1 n 1 c2*=i c2 i c2%=mod c2 mod for j in range(1,b+1):
    c2*=pow(j,mod-2,mod)
    c2%=mod j range(1,b+1) range 1 b+1 b 1 c2*=pow(j,mod-2,mod) c2 pow(j,mod-2,mod) pow j mod-2 mod 2 mod c2%=mod c2 mod ans=pow(2,n,mod)-1 ans pow(2,n,mod)-1 pow(2,n,mod) pow 2 n mod 1 print((ans-c1-c2)%mod) print (ans-c1-c2)%mod ans-c1-c2 ans-c1 ans c1 c2 mod c2%=mod mod c2 c2*=pow(j,mod-2,mod) pow(j,mod-2,mod) c2 c1=1 1 c1 a,b=map(int,input().split()) map(int,input().split()) a b=map(int,input().split()) map(int,input().split()) b c1*=pow(j,mod-2,mod) pow(j,mod-2,mod) c1 c2=1 1 c2 c1%=mod mod c1 mod=10**9+7 10**9+7 mod c2*=i i c2 ans=pow(2,n,mod)-1 pow(2,n,mod)-1 ans n,a,b=map(int,input().split()) map(int,input().split()) n c1%=mod mod c1 c2%=mod mod c2 c1*=i i c1
import math


n,a,b=map(int,input().split())
mod=10**9+7

c1=1
c2=1

for i in range(n-a+1,n+1):
    c1*=i
    c1%=mod
for j in range(1,a+1):
    c1*=pow(j,mod-2,mod)
    c1%=mod
    
for i in range(n-b+1,n+1):
    c2*=i
    c2%=mod
for j in range(1,b+1):
    c2*=pow(j,mod-2,mod)
    c2%=mod

ans=pow(2,n,mod)-1

print((ans-c1-c2)%mod)
