Buggy python submission (verdict: Runtime Error):
from collections import deque
S = deque(list(input()))
Q = int(input())

flag = 0
for i in range(Q):
    query = input().split()
    if query[0] == '1':
        flag = flag ^ 1
    elif query[0] == '2':
        if flag == 0:
            if query[1] == '1':
                S.appendleft(query[2])
            else:
                S.append(query[2])
        else:
            if query[1] == '1':
                S.append(query[2])
            else:
                S.appendleft(query[2])
if flag == 0:
    print(''.join(S))
else:
    print(''.join(S[::-1]))

Fixed submission:
from collections import deque
S = deque(list(input()))
Q = int(input())

flag = 0
for i in range(Q):
    query = input().split()
    if query[0] == '1':
        flag = flag ^ 1
    elif query[0] == '2':
        if flag == 0:
            if query[1] == '1':
                S.appendleft(query[2])
            else:
                S.append(query[2])
        else:
            if query[1] == '1':
                S.append(query[2])
            else:
                S.appendleft(query[2])
if flag == 0:
    print(''.join(S))
else:
    # deque型はスライスで取り出せない print(''.join(S[::-1]))
    S.reverse()
    print(''.join(S))

Buggy python submission (verdict: Runtime Error):
from collections import deque
S = deque(list(input()))
Q = int(input())

flag = 0
for i in range(Q):
    query = input().split()
    if query[0] == '1':
        flag = flag ^ 1
    elif query[0] == '2':
        if flag == 0:
            if query[1] == '1':
                S.appendleft(query[2])
            else:
                S.append(query[2])
        else:
            if query[1] == '1':
                S.append(query[2])
            else:
                S.appendleft(query[2])
if flag == 0:
    print(''.join(S))
else:
    print(''.join(S[::-1]))

Fixed submission:
from collections import deque
S = deque(list(input()))
Q = int(input())

flag = 0
for i in range(Q):
    query = input().split()
    if query[0] == '1':
        flag = flag ^ 1
    elif query[0] == '2':
        if flag == 0:
            if query[1] == '1':
                S.appendleft(query[2])
            else:
                S.append(query[2])
        else:
            if query[1] == '1':
                S.append(query[2])
            else:
                S.appendleft(query[2])
if flag == 0:
    print(''.join(S))
else:
    # deque型はスライスで取り出せない print(''.join(S[::-1]))
    S.reverse()
    print(''.join(S))

Buggy python submission (verdict: Time Limit Exceeded):
S = input()
Q = int(input())


for i in range(Q):
    query = input().split()
    if query[0] == '1':
        S = S[::-1]
    elif query[1] == '1':
        S = query[2] + S
    else:
        S = S + query[2]
print(S)

Fixed submission:
from collections import deque
S = deque(list(input()))
Q = int(input())

flag = 0
for i in range(Q):
    query = input().split()
    if query[0] == '1':
        flag = flag ^ 1
    elif query[0] == '2':
        if flag == 0:
            if query[1] == '1':
                S.appendleft(query[2])
            else:
                S.append(query[2])
        else:
            if query[1] == '1':
                S.append(query[2])
            else:
                S.appendleft(query[2])
if flag == 0:
    print(''.join(S))
else:
    # deque型はスライスで取り出せない print(''.join(S[::-1]))
    S.reverse()
    print(''.join(S))