Merkkijono

l = list(raw_input().upper())
z = 0
while (z + 1) < len(l):
  if l[z] == l[z+1]:
    x = z
    y = l[z]
    while l[x] == l[x+1]:
      del l[x]
      if len(l) == 1:
        break
    del l[x]
    z = -1
  z += 1
s = ""
print s.join(l)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 7, in <module>
    while l[x] == l[x+1]:
IndexError: list index out of range

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED