Merkkijono

l = list(raw_input().upper())
z = 0
a = 0
y = len(l)
for x in range(0,1000):
  if (z+1) < len(l):
    if l[z] == l[z+1]:
      while l[z] == l[z+1]:
        del l[z]
        if (z+1) == len(l):
          break
      del l[z]
      z = 0
    else:
      z += 1
s = ""
print s.join(l)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER