[백준] 1439번 뒤집기

import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		
		Scanner kb = new Scanner(System.in);
		
		String s = kb.next();

		String check = "";
		check += s.charAt(0);
		
		for(int i=1; i<s.length(); i++) {
			if(s.charAt(i-1) != s.charAt(i)) {
				check += s.charAt(i);
			}
		}
		
		int countZero = 0;
		int countOne = 0;
		
		for(char x: check.toCharArray()) {
			if(x == '0') {
				countZero++;
			}else if(x == '1'){
				countOne++;
			}
		}
		
		System.out.println(Math.min(countZero, countOne));
		
	}


}