Merkkijono

orig = input()

pos, pos2 = 0, 0

while True:
    if orig[pos] == orig[pos+1]:
        pos2 = pos+1
        while pos2 < len(orig) and orig[pos] == orig[pos2]:
            pos2 += 1
        orig = orig[:pos] + orig[pos2:]
        if pos > 0:
            pos -= 1
    else:
        pos += 1
    #print(orig)
    #print(" "*pos+'^')
    if pos >= len(orig)-1:
        break

print(orig)

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