Merkkijono

sana = input()

while True:
    length = len(sana)
    ensimmainen = -1
    for i in range(length - 1):
        if sana[i] == sana[i + 1]:
            ensimmainen = i
            break
    if ensimmainen == -1 or length == 1:
        break
    alku = ensimmainen
    loppu = ensimmainen + 1
    while True:
        while alku != 0 and sana[alku - 1] == sana[alku]:
            alku -= 1
        while loppu != length - 1 and sana[loppu + 1] == sana[loppu]:
            loppu += 1
        # if alku != 0 and loppu != length - 1 and sana[alku - 1] == sana[loppu + 1]:
        #     alku -= 1
        #     loppu += 1
        else:
            break
    sana = sana[:alku:] + sana[loppu + 1::]
print(sana)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED