뒤집기

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;
import java.util.Stack;

class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        int zeroChunk = 0;
        int oneChunk = 0;
        char c = s.charAt(0);

        if (c == '1') {
            oneChunk++;
        } else {
            zeroChunk++;
        }

        for (char n : s.toCharArray()) {
            if(n != c){
                if(n == '1') {
                    oneChunk++;
                }else {
                    zeroChunk++;
                }
                c = n;
            }
        }
        System.out.println(Math.min(zeroChunk, oneChunk));
    }
}