Buggy python submission (verdict: Runtime Error):
X = input()
# X = 'SSTTST'
# X = 'TSSTTTSS'

# naive case
# len_prev = -1
# while len_prev != len(X):
#     len_prev = len(X)
#     X = X.replace('ST', '')
# print(len(X))


i = 0
cnt = []
X += " "
cur = 1
for i in range(len(X) - 1):
    if X[i] == X[i + 1]:
        cur += 1
    else:
        cnt.append((X[i], cur))
        cur = 1

total = 0
for i in range(len(cnt) - 1):
    if cnt[i][0] == 'S':
        if cnt[i][1] > cnt[i + 1][1]:
            if i + 2 < len(cnt) - 1:
                cnt[i + 2][1] += cnt[i][1] - cnt[i + 1][1]
        total += min(cnt[i][1], cnt[i + 1][1])
print(len(X) - 1 - 2 * total)


Fixed submission:
#!/usr/bin/env python
# -*- coding:utf-8 -*-

x = input()
n = len(x)

s, t = 0, 0
cnt = 0
for i in range(n):
    if x[i] == 'T':
        if s > 0:
            s -= 1
            cnt += 2
    elif x[i] == 'S':
        s += 1

# i = 0
# s = 0
# t = 0
# cnt = 0
# while i < n:
#     while i < n and x[i] == 'T':
#         i += 1
#         t += 1
#     tmp = min(t, s)
#     cnt += tmp * 2
#     if t - tmp == 0:
#         s -= tmp
#     else:
#         s = 0
#         t = 0

#     while i < n and x[i] == 'S':
#         i += 1
#         s += 1
print(n - cnt)

Buggy python submission (verdict: Runtime Error):

X = input()
# X = 'SSTTST'
# X = 'TSSTTTSS'

# naive case
# len_prev = -1
# while len_prev != len(X):
#     len_prev = len(X)
#     X = X.replace('ST', '')
# print(len(X))


i = 0
cnt = []
X += " "
cur = 1
for i in range(len(X) - 1):
    if X[i] == X[i + 1]:
        cur += 1
    else:
        cnt.append((X[i], cur))
        cur = 1

total = 0
for i in range(len(cnt) - 1):
    if cnt[i][0] == 'S':
        if cnt[i][1] > cnt[i + 1][1]:
            if i + 2 < len(cnt):
                cnt[i + 2][1] += cnt[i][1] - cnt[i + 1][1]
        total += min(cnt[i][1], cnt[i + 1][1])
print(len(X) - 1 - 2 * total)


Fixed submission:
#!/usr/bin/env python
# -*- coding:utf-8 -*-

x = input()
n = len(x)

s, t = 0, 0
cnt = 0
for i in range(n):
    if x[i] == 'T':
        if s > 0:
            s -= 1
            cnt += 2
    elif x[i] == 'S':
        s += 1

# i = 0
# s = 0
# t = 0
# cnt = 0
# while i < n:
#     while i < n and x[i] == 'T':
#         i += 1
#         t += 1
#     tmp = min(t, s)
#     cnt += tmp * 2
#     if t - tmp == 0:
#         s -= tmp
#     else:
#         s = 0
#         t = 0

#     while i < n and x[i] == 'S':
#         i += 1
#         s += 1
print(n - cnt)

Buggy python submission (verdict: Time Limit Exceeded):
X = input()

len_prev = -1
while len_prev != len(X):
    len_prev = len(X)
    X = X.replace('ST', '')
print(len(X))


Fixed submission:
#!/usr/bin/env python
# -*- coding:utf-8 -*-

x = input()
n = len(x)

s, t = 0, 0
cnt = 0
for i in range(n):
    if x[i] == 'T':
        if s > 0:
            s -= 1
            cnt += 2
    elif x[i] == 'S':
        s += 1

# i = 0
# s = 0
# t = 0
# cnt = 0
# while i < n:
#     while i < n and x[i] == 'T':
#         i += 1
#         t += 1
#     tmp = min(t, s)
#     cnt += tmp * 2
#     if t - tmp == 0:
#         s -= tmp
#     else:
#         s = 0
#         t = 0

#     while i < n and x[i] == 'S':
#         i += 1
#         s += 1
print(n - cnt)

Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin/env python
# -*- coding:utf-8 -*-

x = input()
s = x.find('ST')
cnt = 0
while s != -1:
    x = x[:s] + x[s+2:]
    cnt += 1
    s = x.find('ST')
#     print(x)
# print(cnt)
print(len(x))


Fixed submission:
#!/usr/bin/env python
# -*- coding:utf-8 -*-

x = input()
n = len(x)

s, t = 0, 0
cnt = 0
for i in range(n):
    if x[i] == 'T':
        if s > 0:
            s -= 1
            cnt += 2
    elif x[i] == 'S':
        s += 1

# i = 0
# s = 0
# t = 0
# cnt = 0
# while i < n:
#     while i < n and x[i] == 'T':
#         i += 1
#         t += 1
#     tmp = min(t, s)
#     cnt += tmp * 2
#     if t - tmp == 0:
#         s -= tmp
#     else:
#         s = 0
#         t = 0

#     while i < n and x[i] == 'S':
#         i += 1
#         s += 1
print(n - cnt)