Buggy python submission (verdict: Time Limit Exceeded):
n,a,b = map(int, input().split())

p = 10 ** 9 + 7
N = 10 ** 5 *5  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)


def f(x):
    if x==1:
        return 2
    elif x==2:
        return 4
    elif x%2==0:
        return f(x//2)**2
    else:
        return f(x//2)**2*2


fact2 = []
fact2num = max(a,b)+2
now = 1
for i in range(fact2num):
    now *= (n-i)
    now %= p
    fact2.append(now)

def ncr(n,r):
    return (fact2[r-1]*factinv[r])%p

print(f(n)-1-ncr(n,a)-ncr(n,b))


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

p = 10 ** 9 + 7
N = 10 ** 5 *5  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)


# def f(x):
#     if x==1:
#         return 2
#     elif x==2:
#         return 4
#     elif x%2==0:
#         return f(x//2)**2
#     else:
#         return f(x//2)**2*2

di131072 = 1
for i in range(131072):
    di131072 *= 2
    di131072 %= p

q = n//131072
r = n%131072
ans = 1
for i in range(q):
    ans *= di131072
    ans %= p
for i in range(r):
    ans *= 2
    ans %= p


fact2 = []
fact2num = max(a,b)+2
now = 1
for i in range(fact2num):
    now *= (n-i)
    now %= p
    fact2.append(now)

def ncr(n,r):
    return (fact2[r-1]*factinv[r])%p


print((ans-1-ncr(n,a)-ncr(n,b))%p)

Buggy python submission (verdict: Time Limit Exceeded):
n,a,b = map(int, input().split())

p = 10 ** 9 + 7
N = 10 ** 5 *5  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)


def f(x):
    if x==1:
        return 2
    elif x==2:
        return 4
    elif x%2==0:
        return f(x//2)**2
    else:
        return f(x//2)**2*2


fact2 = []
fact2num = max(a,b)+2
now = 1
for i in range(fact2num):
    now *= (n-i)
    now %= p
    fact2.append(now)

def ncr(n,r):
    return (fact2[r-1]*factinv[r])%p

print(f(n)-1-ncr(n,a)-ncr(n,b))


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

p = 10 ** 9 + 7
N = 10 ** 5 *5  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)


# def f(x):
#     if x==1:
#         return 2
#     elif x==2:
#         return 4
#     elif x%2==0:
#         return f(x//2)**2
#     else:
#         return f(x//2)**2*2

di131072 = 1
for i in range(131072):
    di131072 *= 2
    di131072 %= p

q = n//131072
r = n%131072
ans = 1
for i in range(q):
    ans *= di131072
    ans %= p
for i in range(r):
    ans *= 2
    ans %= p


fact2 = []
fact2num = max(a,b)+2
now = 1
for i in range(fact2num):
    now *= (n-i)
    now %= p
    fact2.append(now)

def ncr(n,r):
    return (fact2[r-1]*factinv[r])%p


print((ans-1-ncr(n,a)-ncr(n,b))%p)