/******************************************************************************

Welcome to GDB Online.
GDB online is an online compiler and debugger tool for C, C++, Python, Java, PHP, Ruby, Perl,
C#, VB, Swift, Pascal, Fortran, Haskell, Objective-C, Assembly, HTML, CSS, JS, SQLite, Prolog.
Code, Compile, Run and Debug online from anywhere in world.

*******************************************************************************/
import java.util.*;

public class Main
{
	public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	}
} import java.util.*; util.* java public class Main
{
	public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	}
} Main public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	} main {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String cubeStr = sc.nextLine(); cubeStr sc.nextLine() sc.nextLine sc int length = cubeStr.length(); length cubeStr.length() cubeStr.length cubeStr List<Character> list = new ArrayList<Character>(); list new ArrayList<Character>() for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    } int i=0; int i=0; i 0 i<length i length i++ i++ i {
	        list.add(cubeStr.charAt(i));
	    } {
	        list.add(cubeStr.charAt(i));
	    } list.add(cubeStr.charAt(i)) list.add list cubeStr.charAt(i) cubeStr.charAt cubeStr i int sequence = 0; sequence 0 int numOfCubesCleared = 0; numOfCubesCleared 0 while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    } sequence < list.size()-1 sequence list.size()-1 list.size() list.size list 1 {
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    } if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        } list.get(sequence) != list.get(sequence+1) list.get(sequence) list.get list sequence list.get(sequence+1) list.get list sequence+1 sequence 1 {
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        } list.remove(sequence) list.remove list sequence list.remove(sequence) list.remove list sequence numOfCubesCleared += 2 numOfCubesCleared 2 sequence = Math.max(0, sequence-1) sequence Math.max(0, sequence-1) Math.max Math 0 sequence-1 sequence 1 {
	            sequence++;
	        } sequence++ sequence System.out.println(numOfCubesCleared) System.out.println System.out System System.out numOfCubesCleared String[] args args public class Main
{
	public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	}
} public class Main
{
	public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	}
} Main
/******************************************************************************

Welcome to GDB Online.
GDB online is an online compiler and debugger tool for C, C++, Python, Java, PHP, Ruby, Perl,
C#, VB, Swift, Pascal, Fortran, Haskell, Objective-C, Assembly, HTML, CSS, JS, SQLite, Prolog.
Code, Compile, Run and Debug online from anywhere in world.

*******************************************************************************/
import java.util.*;

public class Main
{
	public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    String cubeStr = sc.nextLine();
	    int length = cubeStr.length();
	    List<Character> list = new ArrayList<Character>();
	    for(int i=0; i<length; i++){
	        list.add(cubeStr.charAt(i));
	    }
	    
	    int sequence = 0;
	    int numOfCubesCleared = 0;
	    
	    while(sequence < list.size()-1){
	        if (list.get(sequence) != list.get(sequence+1)){
	            list.remove(sequence);
	            list.remove(sequence);
	            numOfCubesCleared += 2;
	            sequence = Math.max(0, sequence-1);
	        }else{
	            sequence++;
	        }
	    }
	    System.out.println(numOfCubesCleared);
		
	}
}
