sts = input('')
stack = []

for ele in sts:
    
    if not stack:
        stack.append(ele)
    else:
        top = stack[-1]
        if top == ele:
            stack.pop() 
        else:
            stack.append(ele)
            
res = ''
while stack:
    res += stack.pop()

a = res[::-1] if res else 0
print(a)