def modinv(a, m):
    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
    u %= m
    if u < 0:
        u += m
    return u

def nCk(N, k, mod):
    ret_val = 1
    for i in range(k):
        ret_val *= (N - i)
        ret_val %= mod
        ret_val *= modinv(i + 1, mod)
        ret_val %= mod
    return ret_val


n, a, b = map(int, input().split())
MOD = 10 ** 9 + 7
all_cnt = pow(2, n, MOD) - 1
a_cnt = nCk(n, a, MOD)
b_cnt = nCk(n, b, MOD)
ans = all_cnt - a_cnt - b_cnt
while ans < 0:
    ans += MOD
print(ans) def modinv(a, m):
    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
    u %= m
    if u < 0:
        u += m
    return u modinv b = m b m u = 1 u 1 v = 0 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 if u < 0:
        u += m
     u < 0 u 0 u += m u m return u u a a m m def nCk(N, k, mod):
    ret_val = 1
    for i in range(k):
        ret_val *= (N - i)
        ret_val %= mod
        ret_val *= modinv(i + 1, mod)
        ret_val %= mod
    return ret_val nCk ret_val = 1 ret_val 1 for i in range(k):
        ret_val *= (N - i)
        ret_val %= mod
        ret_val *= modinv(i + 1, mod)
        ret_val %= mod
     i range(k) range k ret_val *= (N - i) ret_val N - i N i ret_val %= mod ret_val mod ret_val *= modinv(i + 1, mod) ret_val modinv(i + 1, mod) modinv i + 1 i 1 mod ret_val %= mod ret_val mod return ret_val ret_val N N k k 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 all_cnt = pow(2, n, MOD) - 1 all_cnt pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 a_cnt = nCk(n, a, MOD) a_cnt nCk(n, a, MOD) nCk n a MOD b_cnt = nCk(n, b, MOD) b_cnt nCk(n, b, MOD) nCk n b MOD ans = all_cnt - a_cnt - b_cnt ans all_cnt - a_cnt - b_cnt all_cnt - a_cnt all_cnt a_cnt b_cnt while ans < 0:
    ans += MOD ans < 0 ans 0 ans += MOD ans MOD print(ans) print ans b_cnt = nCk(n, b, MOD) nCk(n, b, MOD) b_cnt all_cnt = pow(2, n, MOD) - 1 pow(2, n, MOD) - 1 all_cnt def nCk(N, k, mod):
    ret_val = 1
    for i in range(k):
        ret_val *= (N - i)
        ret_val %= mod
        ret_val *= modinv(i + 1, mod)
        ret_val %= mod
    return ret_val def nCk(N, k, mod):
    ret_val = 1
    for i in range(k):
        ret_val *= (N - i)
        ret_val %= mod
        ret_val *= modinv(i + 1, mod)
        ret_val %= mod
    return ret_val nCk MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD ans = all_cnt - a_cnt - b_cnt all_cnt - a_cnt - b_cnt ans b = map(int, input().split()) map(int, input().split()) b def modinv(a, m):
    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
    u %= m
    if u < 0:
        u += m
    return u def modinv(a, m):
    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
    u %= m
    if u < 0:
        u += m
    return u modinv n, a, b = map(int, input().split()) map(int, input().split()) n a, b = map(int, input().split()) map(int, input().split()) a a_cnt = nCk(n, a, MOD) nCk(n, a, MOD) a_cnt ans += MOD MOD ans
def modinv(a, m):
    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
    u %= m
    if u < 0:
        u += m
    return u

def nCk(N, k, mod):
    ret_val = 1
    for i in range(k):
        ret_val *= (N - i)
        ret_val %= mod
        ret_val *= modinv(i + 1, mod)
        ret_val %= mod
    return ret_val


n, a, b = map(int, input().split())
MOD = 10 ** 9 + 7
all_cnt = pow(2, n, MOD) - 1
a_cnt = nCk(n, a, MOD)
b_cnt = nCk(n, b, MOD)
ans = all_cnt - a_cnt - b_cnt
while ans < 0:
    ans += MOD
print(ans)
