Buggy python submission (verdict: Time Limit Exceeded):
import bisect
import sys
input=sys.stdin.readline
k=int(input())
l=list(map(int,input().split()))
l.sort()
ans=0
i=0
n=k
while i<n:
    s=l[-1]
    b=1
    while b<=s:
        b*=2
    g=b-s
    p=bisect.bisect_left(l,g)
    if p==len(l)-1:
        l.pop(-1)
        i+=1
        continue
    else:
        if l[p]==g:
            l.pop(-1)
            l.pop(p)
            i+=2
            ans+=1
        else:
            l.pop(-1)
            i+=1
print(ans)


Fixed submission:
from bisect import bisect_left
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
A.sort()
t=0
for i in range(N):
    while 2**t<=A[i]:
        if 2**t<=A[i]<2**(t+1):
            break
        t+=1
    B[i]=2**(t+1)-A[i]
i=N-1
count=0
flag=[0]*N
for i in range(N-1,0,-1):
    if flag[i]==1:
        continue
    flag[i]=1
    b=bisect_left(A,B[i])
    if A[b]==B[i] and flag[b]==0:
        flag[i]=1
        flag[b]=1
        A[b]-=1
        count+=1
print(count)

Buggy python submission (verdict: Runtime Error):
import bisect
import sys
input=sys.stdin.readline
k=int(input())
l=list(map(int,input().split()))
l.sort()
ans=0
i=0
n=k
while i<n:
    s=l[-1]
    b=1
    while b<=s:
        b*=2
    g=b-s
    p=bisect.bisect_left(l,g)
    if p==len(l):
        l.pop(-1)
        i+=1
        continue
    else:
        if l[p]==g:
            l.pop(-1)
            l.pop(p)
            i+=2
            ans+=1
        else:
            l.pop(-1)
            i+=1
print(ans)


Fixed submission:
from bisect import bisect_left
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
A.sort()
t=0
for i in range(N):
    while 2**t<=A[i]:
        if 2**t<=A[i]<2**(t+1):
            break
        t+=1
    B[i]=2**(t+1)-A[i]
i=N-1
count=0
flag=[0]*N
for i in range(N-1,0,-1):
    if flag[i]==1:
        continue
    flag[i]=1
    b=bisect_left(A,B[i])
    if A[b]==B[i] and flag[b]==0:
        flag[i]=1
        flag[b]=1
        A[b]-=1
        count+=1
print(count)

Buggy python submission (verdict: Runtime Error):
import bisect
k=int(input())
l=list(map(int,input().split()))
l.sort()
ans=0
i=0
n=k
while i<n:
    s=l[-1]
    b=1
    while b<=s:
        b*=2
    g=b-s
    p=bisect.bisect_left(l,g)
    if p==len(l):
        l.pop(-1)
        i+=1
        continue
    else:
        if l[p]==g:
            l.pop(-1)
            l.pop(p)
            i+=2
            ans+=1
        else:
            l.pop(-1)
            i+=1
print(ans)


Fixed submission:
from bisect import bisect_left
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
A.sort()
t=0
for i in range(N):
    while 2**t<=A[i]:
        if 2**t<=A[i]<2**(t+1):
            break
        t+=1
    B[i]=2**(t+1)-A[i]
i=N-1
count=0
flag=[0]*N
for i in range(N-1,0,-1):
    if flag[i]==1:
        continue
    flag[i]=1
    b=bisect_left(A,B[i])
    if A[b]==B[i] and flag[b]==0:
        flag[i]=1
        flag[b]=1
        A[b]-=1
        count+=1
print(count)

Buggy python submission (verdict: Time Limit Exceeded):
import bisect
n=int(input())
l=list(map(int,input().split()))
l.sort()
ans=0
i=0
while i<n:
    s=l[n-i-1]
    b=1
    while b<=s:
        b*=2
    g=b-s
    p=bisect.bisect_left(l[:n-i-1],g)
    if p==n-i-1:
        i+=1
        continue
    else:
        if l[p]==g:
            l.pop(n-i-1)
            l.pop(p)
            i+=2
            ans+=1
        else:
            i+=1
print(ans)


Fixed submission:
from bisect import bisect_left
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
A.sort()
t=0
for i in range(N):
    while 2**t<=A[i]:
        if 2**t<=A[i]<2**(t+1):
            break
        t+=1
    B[i]=2**(t+1)-A[i]
i=N-1
count=0
flag=[0]*N
for i in range(N-1,0,-1):
    if flag[i]==1:
        continue
    flag[i]=1
    b=bisect_left(A,B[i])
    if A[b]==B[i] and flag[b]==0:
        flag[i]=1
        flag[b]=1
        A[b]-=1
        count+=1
print(count)

Buggy python submission (verdict: Time Limit Exceeded):
import bisect
n=int(input())
l=list(map(int,input().split()))
l.sort()
ans=0
i=0
while i<n:
    s=l[n-i-1]
    b=1
    while b<=s:
        b*=2
    g=b-s
    p=bisect.bisect_left(l[:n-i-1],g)
    if p==n-i-1:
        i+=1
        continue
    else:
        if l[p]==g:
            l.pop(n-i-1)
            l.pop(p)
            i+=2
            ans+=1
print(ans)


Fixed submission:
from bisect import bisect_left
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
A.sort()
t=0
for i in range(N):
    while 2**t<=A[i]:
        if 2**t<=A[i]<2**(t+1):
            break
        t+=1
    B[i]=2**(t+1)-A[i]
i=N-1
count=0
flag=[0]*N
for i in range(N-1,0,-1):
    if flag[i]==1:
        continue
    flag[i]=1
    b=bisect_left(A,B[i])
    if A[b]==B[i] and flag[b]==0:
        flag[i]=1
        flag[b]=1
        A[b]-=1
        count+=1
print(count)

Buggy python submission (verdict: Runtime Error):
import bisect
n=int(input())
l=list(map(int,input().split()))
l.sort()
ans=0
for i in range(n-1):
    s=l[n-i-1]
    b=1
    while b<=s:
        b*=2
    g=b-s
    p=bisect.bisect_left(l[:n-i-1],g)
    if p==n-i-1:
        continue
    else:
        if l[p]==g:
            l.pop(n-i-1)
            l.pop(p)
            n-=2
            ans+=1
print(ans)

Fixed submission:
from bisect import bisect_left
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
A.sort()
t=0
for i in range(N):
    while 2**t<=A[i]:
        if 2**t<=A[i]<2**(t+1):
            break
        t+=1
    B[i]=2**(t+1)-A[i]
i=N-1
count=0
flag=[0]*N
for i in range(N-1,0,-1):
    if flag[i]==1:
        continue
    flag[i]=1
    b=bisect_left(A,B[i])
    if A[b]==B[i] and flag[b]==0:
        flag[i]=1
        flag[b]=1
        A[b]-=1
        count+=1
print(count)