def modComb(n,r,mod):
    nume = 1
    deno = 1
    for i in range(r):
        nume = nume*(n-i) % mod
        deno = deno*(i+1) % mod
    return nume*pow(deno, mod-2, mod) % mod

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

mod = 10**9+7

ans = (pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod)) % mod

print(ans) def modComb(n,r,mod):
    nume = 1
    deno = 1
    for i in range(r):
        nume = nume*(n-i) % mod
        deno = deno*(i+1) % mod
    return nume*pow(deno, mod-2, mod) % mod modComb nume = 1 nume 1 deno = 1 deno 1 for i in range(r):
        nume = nume*(n-i) % mod
        deno = deno*(i+1) % mod
     i range(r) range r nume = nume*(n-i) % mod nume nume*(n-i) % mod nume*(n-i) nume n-i n i mod deno = deno*(i+1) % mod deno deno*(i+1) % mod deno*(i+1) deno i+1 i 1 mod return nume*pow(deno, mod-2, mod) % mod nume*pow(deno, mod-2, mod) % mod nume*pow(deno, mod-2, mod) nume pow(deno, mod-2, mod) pow deno mod-2 mod 2 mod mod n n r r mod mod 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 ans = (pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod)) % mod ans (pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod)) % mod pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod) pow(2, n, mod) -1 -modComb(n,a,mod) pow(2, n, mod) -1 pow(2, n, mod) pow 2 n mod 1 modComb(n,a,mod) modComb n a mod modComb(n,b,mod) modComb n b mod mod print(ans) print ans def modComb(n,r,mod):
    nume = 1
    deno = 1
    for i in range(r):
        nume = nume*(n-i) % mod
        deno = deno*(i+1) % mod
    return nume*pow(deno, mod-2, mod) % mod def modComb(n,r,mod):
    nume = 1
    deno = 1
    for i in range(r):
        nume = nume*(n-i) % mod
        deno = deno*(i+1) % mod
    return nume*pow(deno, mod-2, mod) % mod modComb n, a, b = map(int, input().split()) map(int, input().split()) n a, b = map(int, input().split()) map(int, input().split()) a ans = (pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod)) % mod (pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod)) % mod ans b = map(int, input().split()) map(int, input().split()) b mod = 10**9+7 10**9+7 mod
def modComb(n,r,mod):
    nume = 1
    deno = 1
    for i in range(r):
        nume = nume*(n-i) % mod
        deno = deno*(i+1) % mod
    return nume*pow(deno, mod-2, mod) % mod

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

mod = 10**9+7

ans = (pow(2, n, mod) -1 -modComb(n,a,mod) - modComb(n,b,mod)) % mod

print(ans)