Buggy python submission (verdict: Runtime Error):
def f(a):q=a[:n];heapify(q);return sum(q)+cumsum([e-heappushpop(q,e)for e in a[n:n-~n]]);from heapq import*;from numpy import*;n,*a=map(int,open(0).read().split());print(max(map(sum,zip(f(a),f([-e for e in a[::-1]])[::-1]))))

Fixed submission:
from heapq import*
n,*a=map(int,open(0).read().split())
b=a[:n]
c=[-i for i in a[n:][::-1]]
d=c[:n]
e=c[n:]
heapify(b)
heapify(d)
s=sum(b)
t=sum(d)
red=[s]
blue=[t]
for i in range(n,n*2):
    s+=a[i]-heappushpop(b,a[i])
    t+=c[i]-heappushpop(d,c[i])
    red+=[s]
    blue+=[t]
print(max(map(sum,zip(red,blue[::-1]))))

#あｈｊｆｋぁｄｓｈｆｌｋじゃｇはｌｋｊｄｊｇｌｋ；あｊｄｇｌｋ；あｄｓｊｇｌ；あｊｓｄｇｌｋ；あｊｓｄｇｌ；かｓ

Buggy python submission (verdict: Runtime Error):
def f(a):
	q=a[:n];s=sum(q);heapify(q)
	for e in a[n:n-~n]:yield s;s+=e-heappushpop(q,e)
from heapq import*;r=raw_input;n,a=r(),map(int,r());print max(map(sum,zip(f(a),list(f([-e for e in a[::-1]]))[::-1])))

Fixed submission:
from heapq import*
n,*a=map(int,open(0).read().split())
b=a[:n]
c=[-i for i in a[n:][::-1]]
d=c[:n]
e=c[n:]
heapify(b)
heapify(d)
s=sum(b)
t=sum(d)
red=[s]
blue=[t]
for i in range(n,n*2):
    s+=a[i]-heappushpop(b,a[i])
    t+=c[i]-heappushpop(d,c[i])
    red+=[s]
    blue+=[t]
print(max(map(sum,zip(red,blue[::-1]))))

#あｈｊｆｋぁｄｓｈｆｌｋじゃｇはｌｋｊｄｊｇｌｋ；あｊｄｇｌｋ；あｄｓｊｇｌ；あｊｓｄｇｌｋ；あｊｓｄｇｌ；かｓ

Buggy python submission (verdict: Time Limit Exceeded):
from heapq import*
from collections import*
n,*a=map(int,open(0).read().split())
ans=-float("inf")
b=a[:n]
c=deque(a[n:])
heapify(b)
s=sum(b)
s2=sum(nsmallest(n,c))
red=[s-s2]
for i in range(n,n*2):
    s+=a[i]-heappushpop(b,a[i])
    c.popleft()
    s2=sum(nsmallest(n,c))
    red+=[s-s2]
print(max(red))

#あｈｊｆｋぁｄｓｈｆｌｋじゃｇはｌｋｊｄｊｇｌｋ；あｊｄｇｌｋ；あｄｓｊｇｌ；あｊｓｄｇｌｋ；あｊｓｄｇｌ；かｓ

Fixed submission:
from heapq import*
n,*a=map(int,open(0).read().split())
b=a[:n]
c=[-i for i in a[n:][::-1]]
d=c[:n]
e=c[n:]
heapify(b)
heapify(d)
s=sum(b)
t=sum(d)
red=[s]
blue=[t]
for i in range(n,n*2):
    s+=a[i]-heappushpop(b,a[i])
    t+=c[i]-heappushpop(d,c[i])
    red+=[s]
    blue+=[t]
print(max(map(sum,zip(red,blue[::-1]))))

#あｈｊｆｋぁｄｓｈｆｌｋじゃｇはｌｋｊｄｊｇｌｋ；あｊｄｇｌｋ；あｄｓｊｇｌ；あｊｓｄｇｌｋ；あｊｓｄｇｌ；かｓ

Buggy python submission (verdict: Time Limit Exceeded):
from heapq import*
n,*a=map(int,open(0).read().split())
#print(a)
ans=-float("inf")
for i in range(n,2*n+1):
    score=0
    tmp=a[:i]
    heapify(tmp)
#    print(tmp)
    for j in range(i-n):
        heappop(tmp)
    score+=sum(tmp)
    tmp=a[i:]
    heapify(tmp)
#    print(tmp)
    score-=sum(heappop(tmp)for r in range(n))

    ans=max(score,ans)
print(ans)

Fixed submission:
from heapq import*
n,*a=map(int,open(0).read().split())
b=a[:n]
c=[-i for i in a[n:][::-1]]
d=c[:n]
e=c[n:]
heapify(b)
heapify(d)
s=sum(b)
t=sum(d)
red=[s]
blue=[t]
for i in range(n,n*2):
    s+=a[i]-heappushpop(b,a[i])
    t+=c[i]-heappushpop(d,c[i])
    red+=[s]
    blue+=[t]
print(max(map(sum,zip(red,blue[::-1]))))

#あｈｊｆｋぁｄｓｈｆｌｋじゃｇはｌｋｊｄｊｇｌｋ；あｊｄｇｌｋ；あｄｓｊｇｌ；あｊｓｄｇｌｋ；あｊｓｄｇｌ；かｓ

Buggy python submission (verdict: Time Limit Exceeded):
from heapq import*
n,*a=map(int,open(0).read().split())
#print(a)
ans=-float("inf")
for i in range(n,2*n+1):
    score=0
    tmp=a[:i]
    heapify(tmp)
#    print(tmp)
    for j in range(i-n):
        heappop(tmp)
    score+=sum(tmp)
    tmp=a[i:]
    heapify(tmp)
#    print(tmp)
    score-=sum(heappop(tmp)for r in range(n))

    ans=max(score,ans)
print(ans)

Fixed submission:
from heapq import*
n,*a=map(int,open(0).read().split())
b=a[:n]
c=[-i for i in a[n:][::-1]]
d=c[:n]
e=c[n:]
heapify(b)
heapify(d)
s=sum(b)
t=sum(d)
red=[s]
blue=[t]
for i in range(n,n*2):
    s+=a[i]-heappushpop(b,a[i])
    t+=c[i]-heappushpop(d,c[i])
    red+=[s]
    blue+=[t]
print(max(map(sum,zip(red,blue[::-1]))))

#あｈｊｆｋぁｄｓｈｆｌｋじゃｇはｌｋｊｄｊｇｌｋ；あｊｄｇｌｋ；あｄｓｊｇｌ；あｊｓｄｇｌｋ；あｊｓｄｇｌ；かｓ