public int solution(String s) {
    	Stack<Character> stack = new Stack<>();

    	int count = 0;

    	Character c;

    	for(int i = 0; i < s.length(); i++){
    		c = s.charAt(i);

    		if(!stack.empty()) {
				if(!stack.peek().equals(c)) {
					stack.pop();

					if(stack.empty())
						count++;
				} else {
					stack.push(c);
				}
			} else {
    			stack.push(c);
			}
		}

		return count;
	}