Buggy python submission (verdict: Runtime Error):
n,a,b=map(int,input().split())
mod = 10**9+7
MAX_N = 10**6

fact = [1]
fact_inv = [0]*(MAX_N+4)
for i in range(MAX_N+3):
    fact.append(fact[-1]*(i+1)%mod)

fact_inv[-1] = pow(fact[-1],mod-2,mod)
for i in range(MAX_N+2,-1,-1):
    fact_inv[i] = fact_inv[i+1]*(i+1)%mod


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod



x=mod_comb_k(n,a,mod)+mod_comb_k(n,b,mod)
y=((pow(2,n)-1)%(10**9+7))
ans=(y-x%(10**9+7))
while ans<0:
          ans+=10**9+7
print(ans)





Fixed submission:
n,a,b=map(int,input().split())
def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk

x=pow(2,n,10**9+7)-1
y=comb(n,a)+comb(n,b)
ans=x-y





while ans<0:
          ans+=10**9+7
print(ans)

Buggy python submission (verdict: Runtime Error):

n,a,b=map(int,input().split
mod = 10**9+7
MAX_N = 10**6

fact = [1]
fact_inv = [0]*(MAX_N+4)
for i in range(MAX_N+3):
    fact.append(fact[-1]*(i+1)%mod)

fact_inv[-1] = pow(fact[-1],mod-2,mod)
for i in range(MAX_N+2,-1,-1):
    fact_inv[i] = fact_inv[i+1]*(i+1)%mod


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod



x=mod_comb_k(n,a,mod)+mod_comb_k(n,b,mod)
y=((pow(2,n)-1)%(10**9+7))
ans=(y-x%(10**9+7))
while ans<0:
          ans+=10**9+7
print(ans)



Fixed submission:
n,a,b=map(int,input().split())
def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk

x=pow(2,n,10**9+7)-1
y=comb(n,a)+comb(n,b)
ans=x-y





while ans<0:
          ans+=10**9+7
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from operator import mul
from functools import reduce
n,a,b=map(int,input().split())
def cmb(n,r):
    r = min(n-r,r)
    if r == 0: return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1,r + 1))
    return over // under

x=cmb(n,a)+cmb(n,b)
y=pow(2,n)-1
ans=(y-x%(10**9+7))
print(ans)



Fixed submission:
n,a,b=map(int,input().split())
def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk

x=pow(2,n,10**9+7)-1
y=comb(n,a)+comb(n,b)
ans=x-y





while ans<0:
          ans+=10**9+7
print(ans)

Buggy python submission (verdict: Runtime Error):
from operator import mul
from functools import reduce
n,a,b=map(int,input(),split())
def cmb(n,r):
    r = min(n-r,r)
    if r == 0: return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1,r + 1))
    return over // under

x=cmb(n,a)+cmb(n,b)
y=pow(2,n)-1
ans=(y-x%(10**9+7))
print(ans)

Fixed submission:
n,a,b=map(int,input().split())
def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk

x=pow(2,n,10**9+7)-1
y=comb(n,a)+comb(n,b)
ans=x-y





while ans<0:
          ans+=10**9+7
print(ans)