Buggy python submission (verdict: Runtime Error):
n, a, b = map(int, input().split())
#res = 2 ** n - 1
res = pow(2, n, mod)
mod = 10**9 + 7

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod

res -= cmb(n,a,mod)
res -= cmb(n,b,mod)

print(res % mod)


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

mod = 10**9 + 7
res = pow(2, n, mod)

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod


A = cmb(n, a, mod)
B = cmb(n, b, mod)

print((res - A - B - 1) % mod)

Buggy python submission (verdict: Time Limit Exceeded):
n, a, b = map(int, input().split())
mod = 10**9 + 7
res = 2**n - 1 

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod

res -= cmb(n,a,mod)
res -= cmb(n,b,mod)

print(res % mod)


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

mod = 10**9 + 7
res = pow(2, n, mod)

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod


A = cmb(n, a, mod)
B = cmb(n, b, mod)

print((res - A - B - 1) % mod)

Buggy python submission (verdict: Runtime Error):
n, a, b = map(int, input().split())
res = 2 ** n - 1

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 10**4
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

res -= cmb(n,a,mod)
res -= cmb(n,b,mod)

print(res)

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

mod = 10**9 + 7
res = pow(2, n, mod)

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod


A = cmb(n, a, mod)
B = cmb(n, b, mod)

print((res - A - B - 1) % mod)

Buggy python submission (verdict: Time Limit Exceeded):
n, a, b = map(int, input().split())
res = 0

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

from functools import lru_cache

@lru_cache(maxsize=1000)
def c(n,k): 
    return 1 if(k<=0 or n<=k) else ( c(n-1, k-1) + c(n-1, k) ) %4

mod = 10**9+7 #出力の制限
#N = 10**4
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, n + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )
    
res = 2 ** n - 1

res -= cmb(n,a,mod)
res -= cmb(n,b,mod)

print(res)


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

mod = 10**9 + 7
res = pow(2, n, mod)

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod


A = cmb(n, a, mod)
B = cmb(n, b, mod)

print((res - A - B - 1) % mod)

Buggy python submission (verdict: Time Limit Exceeded):
n, a, b = map(int, input().split())
res = 0

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
#N = 10**4
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, n + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

    
#res = cmb(n,3,mod)
for i in range(1, n+1):
    res += cmb(n,i,mod)
res -= cmb(n,a,mod)
res -= cmb(n,b,mod)

print(res)

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

mod = 10**9 + 7
res = pow(2, n, mod)

def cmb(n, r, mod):
    r = min(n-r, r)
    if r == 0:
        return 1
    over, under = 1, 1
    for i in range(1, r+1):
        over = over * (n-i+1) % mod
        under = under * i % mod
    inv = pow(under, mod-2, mod)
    return over * inv % mod


A = cmb(n, a, mod)
B = cmb(n, b, mod)

print((res - A - B - 1) % mod)