Stones

import java.util.Scanner;

/**
 *
 * @author tuukkatu
 */
public class JavaApplication1 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) 
    {
        IO io = new IO();
	
	String stones = io.next();
        
        int counter = 0;
        
        int pointer1 = 0;
        
        int pointer2 = 1;
        
        while (pointer2 < stones.length())
        {
            if (stones.charAt(pointer2) == stones.charAt(pointer1))
            {
                pointer1++;
                
                pointer2++;
                
                counter++;
            }
            else
            {
                pointer1++;
                
                pointer2++;
            }
        }
      
        io.println(counter);
	
	io.close();
    }
}
        
    
    

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED