Buggy python submission (verdict: Time Limit Exceeded):
from itertools import count
from itertools import chain

def gen_check_numbers(n):
    center = n // 2
    l2 = chain.from_iterable(zip(reversed(range(1, center + 1)), range(center + 1 , n + 1)))
    return l2

def main():
    n = int(input())
    l = [ int(input().rstrip()) for i in range(n)]

    ans = 0
    center = n // 2
    for i in gen_check_numbers(n):
        i1 = l.index(i)
        if i <= center:
            i2 = l.index(i + 1)
            if( i2 < i1):
                l.remove(i)
                l.insert(0,i)
                ans += 1
        else:
            i2 = l.index(i - 1)
            if( i1 < i2):
                l.remove(i)
                l.append(i)
                ans += 1
    print(ans)

if __name__ == '__main__':
    main()


Fixed submission:
def main():
    n = int(input())
    l = [ int(input().rstrip()) for i in range(n)]

    s = {}
    for i in l:
        if i - 1 in s:
            s[i] = s[i - 1] + 1
            del s[i - 1]
        else:
            s[i] = 1
    print(n - max(s.values()))

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
from itertools import count
n = int(input())
l = [ int(input()) for i in range(n)]
ans = tuple(sorted(l))

checked = set()

s = [(l, 0)]
for loop_count in count():
    #print(s, checked)
    tl, ns = s.pop(0)
    #print(loop_count, ns, len(s), len(checked))
    if tuple(tl) in checked:
        continue
    if ans == tuple(tl):
        print(ns)
        break
    for i in range(n):
        n1 = list(tl)
        if i != n - 1 and i != 0 and n1[i] != n1[i-1] + 1:
            c = n1.pop(i)
            n1.append(c)
            if(tuple(n1) not in checked):
                s.append((n1, ns+1))
        n2 = list(tl)
        if i != 0 and i != n - 1 and n2[i] + 1 != n2[i+1]:
            c = n2.pop(i)
            n2.insert(0, c)
            if(tuple(n2) not in checked):
                s.append((n2, ns+1))
    checked.add(tuple(tl))


Fixed submission:
def main():
    n = int(input())
    l = [ int(input().rstrip()) for i in range(n)]

    s = {}
    for i in l:
        if i - 1 in s:
            s[i] = s[i - 1] + 1
            del s[i - 1]
        else:
            s[i] = 1
    print(n - max(s.values()))

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
from itertools import count
n = int(input())
l = [ int(input()) for i in range(n)]
ans = tuple(sorted(l))

checked = set()

s = [(l, 0)]
for loop_count in count():
    #print(loop_count, len(s), len(checked))
    #print(s, checked)
    tl, ns = s.pop(0)
    if tuple(tl) in checked:
        continue
    if ans == tuple(tl):
        print(ns)
        break
    for i in range(n):
        n1 = list(tl)
        c = n1.pop(i)
        n1.append(c)
        if(tuple(n1) not in checked):
            s.append((n1, ns+1))
        n2 = list(tl)
        c = n2.pop(i)
        n2.insert(0, c)
        if(tuple(n2) not in checked):
            s.append((n2, ns+1))
    checked.add(tuple(tl))


Fixed submission:
def main():
    n = int(input())
    l = [ int(input().rstrip()) for i in range(n)]

    s = {}
    for i in l:
        if i - 1 in s:
            s[i] = s[i - 1] + 1
            del s[i - 1]
        else:
            s[i] = 1
    print(n - max(s.values()))

if __name__ == '__main__':
    main()