import math

n, a, b = map(int, input().split())
MOD = 1000000000 + 7

inv = [1, 1]
com = [0, n]
for i in range(2, max(a, b) + 1):
    inv.append(MOD - inv[MOD % i] * (MOD // i) % MOD)
    com.append(com[i - 1] * (n - i + 1) * inv[i] % MOD)

print((pow(2, n, MOD) - com[a] - com[b] - 1) % 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 = 1000000000 + 7 MOD 1000000000 + 7 1000000000 7 inv = [1, 1] inv [1, 1] 1 1 com = [0, n] com [0, n] 0 n for i in range(2, max(a, b) + 1):
    inv.append(MOD - inv[MOD % i] * (MOD // i) % MOD)
    com.append(com[i - 1] * (n - i + 1) * inv[i] % MOD) i range(2, max(a, b) + 1) range 2 max(a, b) + 1 max(a, b) max a b 1 inv.append(MOD - inv[MOD % i] * (MOD // i) % MOD) inv.append inv append MOD - inv[MOD % i] * (MOD // i) % MOD MOD inv[MOD % i] * (MOD // i) % MOD inv[MOD % i] * (MOD // i) inv[MOD % i] inv MOD % i MOD i MOD // i MOD i MOD com.append(com[i - 1] * (n - i + 1) * inv[i] % MOD) com.append com append com[i - 1] * (n - i + 1) * inv[i] % MOD com[i - 1] * (n - i + 1) * inv[i] com[i - 1] * (n - i + 1) com[i - 1] com i - 1 i 1 n - i + 1 n - i n i 1 inv[i] inv i MOD print((pow(2, n, MOD) - com[a] - com[b] - 1) % MOD) print (pow(2, n, MOD) - com[a] - com[b] - 1) % MOD pow(2, n, MOD) - com[a] - com[b] - 1 pow(2, n, MOD) - com[a] - com[b] pow(2, n, MOD) - com[a] pow(2, n, MOD) pow 2 n MOD com[a] com a com[b] com b 1 MOD inv = [1, 1] [1, 1] inv n, a, b = map(int, input().split()) map(int, input().split()) n com = [0, n] [0, n] com a, b = map(int, input().split()) map(int, input().split()) a MOD = 1000000000 + 7 1000000000 + 7 MOD b = map(int, input().split()) map(int, input().split()) b
import math

n, a, b = map(int, input().split())
MOD = 1000000000 + 7

inv = [1, 1]
com = [0, n]
for i in range(2, max(a, b) + 1):
    inv.append(MOD - inv[MOD % i] * (MOD // i) % MOD)
    com.append(com[i - 1] * (n - i + 1) * inv[i] % MOD)

print((pow(2, n, MOD) - com[a] - com[b] - 1) % MOD)
