from math import factorial

n,a,b = map(int,input().split())
MOD = 10**9 + 7
xa = 1
xb = 1

k1 = pow(2,n,MOD)
A = pow(factorial(a),MOD-2,MOD)
B = pow(factorial(b),MOD-2,MOD) 

for i in range(a):
  xa = xa*(n-i)%MOD
for j in range(b):
  xb = xb*(n-j)%MOD

ans = (k1 - (A*xa) - (B*xb) - 1)%MOD 

print(ans) from math import factorial 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 xa = 1 xa 1 xb = 1 xb 1 k1 = pow(2,n,MOD) k1 pow(2,n,MOD) pow 2 n MOD A = pow(factorial(a),MOD-2,MOD) A pow(factorial(a),MOD-2,MOD) pow factorial(a) factorial a MOD-2 MOD 2 MOD B = pow(factorial(b),MOD-2,MOD) B pow(factorial(b),MOD-2,MOD) pow factorial(b) factorial b MOD-2 MOD 2 MOD for i in range(a):
  xa = xa*(n-i)%MOD i range(a) range a xa = xa*(n-i)%MOD xa xa*(n-i)%MOD xa*(n-i) xa n-i n i MOD for j in range(b):
  xb = xb*(n-j)%MOD j range(b) range b xb = xb*(n-j)%MOD xb xb*(n-j)%MOD xb*(n-j) xb n-j n j MOD ans = (k1 - (A*xa) - (B*xb) - 1)%MOD ans (k1 - (A*xa) - (B*xb) - 1)%MOD k1 - (A*xa) - (B*xb) - 1 k1 - (A*xa) - (B*xb) k1 - (A*xa) k1 A*xa A xa B*xb B xb 1 MOD print(ans) print ans xa = xa*(n-i)%MOD xa*(n-i)%MOD xa b = map(int,input().split()) map(int,input().split()) b MOD = 10**9 + 7 10**9 + 7 MOD A = pow(factorial(a),MOD-2,MOD) pow(factorial(a),MOD-2,MOD) A k1 = pow(2,n,MOD) pow(2,n,MOD) k1 B = pow(factorial(b),MOD-2,MOD) pow(factorial(b),MOD-2,MOD) B ans = (k1 - (A*xa) - (B*xb) - 1)%MOD (k1 - (A*xa) - (B*xb) - 1)%MOD ans a,b = map(int,input().split()) map(int,input().split()) a xb = xb*(n-j)%MOD xb*(n-j)%MOD xb n,a,b = map(int,input().split()) map(int,input().split()) n xb = 1 1 xb xa = 1 1 xa
from math import factorial

n,a,b = map(int,input().split())
MOD = 10**9 + 7
xa = 1
xb = 1

k1 = pow(2,n,MOD)
A = pow(factorial(a),MOD-2,MOD)
B = pow(factorial(b),MOD-2,MOD) 

for i in range(a):
  xa = xa*(n-i)%MOD
for j in range(b):
  xb = xb*(n-j)%MOD

ans = (k1 - (A*xa) - (B*xb) - 1)%MOD 

print(ans)