Problem: Polycarp likes numbers that are divisible by 3.

He has a huge number s. Polycarp wants to cut from it the maximum number of numbers that are divisible by 3. To do this, he makes an arbitrary number of vertical cuts between pairs of adjacent digits. As a result, after m such cuts, there will be m+1 parts in total. Polycarp analyzes each of the obtained numbers and finds the number of those that are divisible by 3.

For example, if the original number is s=3121, then Polycarp can cut it into three parts with two cuts: 3|1|21. As a result, he will get two numbers that are divisible by 3.

Polycarp can make an arbitrary number of vertical cuts, where each cut is made between a pair of adjacent digits. The resulting numbers cannot contain extra leading zeroes (that is, the number can begin with 0 if and only if this number is exactly one character '0'). For example, 007, 01 and 00099 are not valid numbers, but 90, 0 and 10001 are valid.

What is the maximum number of numbers divisible by 3 that Polycarp can obtain?

Input

The first line of the input contains a positive integer s. The number of digits of the number s is between 1 and 2⋅10^5, inclusive. The first (leftmost) digit is not equal to 0.

Output

Print the maximum number of numbers divisible by 3 that Polycarp can get by making vertical cuts in the given number s.

Examples

Input

3121


Output

2


Input

6


Output

1


Input

1000000000000000000000000000000000


Output

33


Input

201920181


Output

4

Note

In the first example, an example set of optimal cuts on the number is 3|1|21.

In the second example, you do not need to make any cuts. The specified number 6 forms one number that is divisible by 3.

In the third example, cuts must be made between each pair of digits. As a result, Polycarp gets one digit 1 and 33 digits 0. Each of the 33 digits 0 forms a number that is divisible by 3.

In the fourth example, an example set of optimal cuts is 2|0|1|9|201|81. The numbers 0, 9, 201 and 81 are divisible by 3.

Solution (in JAVA):

Solution:
import java.io.*;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.*;
import java.lang.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Contest {
	//static ArrayList<Integer> prime=new ArrayList();
	
	   public static TreeMap<Long,Integer> t1=new TreeMap();
	   public static void solve()
	    {
	      long m=1;
	      for(int j=2;j<=1000;j++)
	      {
	         
	          if(isprime(j))
	          {
	              m=m*j;
	              if(m>1000000)
	              {
	                  break;
	              }else{
	                  t1.put(m,1);
	              }
	          }
	      }
	    }
	
    public static int gcd(int n1, int n2)
    {
        if (n2 != 0)
            return gcd(n2, n1 % n2);
        else
            return n1;
    }
	
//////////////////	
	public static class trie {
        int x,y,z;
        trie (int x,int y,int z){
            this.x=x;
            this.y=y;
            this.z=z;
        }
	
	} 
        
	public static class pair {
        int x,y;
        pair (int x,int y){
            this.x=x;
            this.y=y;
        }
        public boolean equals(Object o) {
        	if(o instanceof pair) {
        		pair p = (pair)o;
        		return (x == p.x && y == p.y);
        	}
        	return false;
        }
        public int hashCode() {
        	return (Integer.hashCode(x) * 3 + Integer.hashCode(y) );
        }
    }
	
//////////////////	
	
	static class Cmp implements Comparator<pair>
	{
		public int compare(pair a,pair b)
		{
			if(a.x==b.x)
			{
				return(a.y-b.y);
			}
			return(a.x-b.x);
		}
	}
	
	
//////////////////
	
	
	
	
//////////////////
	
	
	
	
	
	   static class FastReader
	   {
		   BufferedReader br;
		   StringTokenizer st;
		   public FastReader()
		   {
			   br = new BufferedReader(new InputStreamReader(System.in));
		   }
		   
		   
		   String next() 
	        { 
	            while (st == null || !st.hasMoreElements()) 
	            { 
	                try
	                { 
	                    st = new StringTokenizer(br.readLine()); 
	                } 
	                catch (IOException  e) 
	                { 
	                    e.printStackTrace(); 
	                } 
	            } 
	            return st.nextToken(); 
	        } 
		   
		   
		   int nextInt()
		   {
			   return Integer.parseInt(next());
		   }
		   long nextLong()
		   {
			   return Long.parseLong(next());
		   }
		   double nextDouble() 
	        { 
	            return Double.parseDouble(next()); 
	        } 
		   
		   String nextLine() 
	        { 
	            String str = ""; 
	            try
	            { 
	                str = br.readLine(); 
	            } 
	            catch (IOException e) 
	            { 
	                e.printStackTrace(); 
	            } 
	            return str; 
	        } 
	   }
	   
////////////////////// 
	//public static ArrayList<Integer> a=new ArrayList();
	   
	  public static ArrayList<Integer> Divisors(int n) 
	   { 
	       // Note that this loop runs till square root 
		  ArrayList<Integer> a=new ArrayList();
		   long sum=0;
	       for (int i=1; i*i<=(n); i++) 
	       { 
	           if (n%i == 0) 
	           { 
	               // If divisors are equal, print only one 
	               if (n/i == i) 
	               {
	                  // printf("%d ", i); 
	            	   sum=sum+1;
	            	   a.add(i);
	               }
	     
	               else // Otherwise print both 
	               {
	                   //printf("%d %d ", i, n/i); 
	            	   sum=sum+2;
	            	   a.add(i);
	            	   a.add(n/i);
	               }
	           } 
	       } 
	       return(a);
	   } 
	   
/////////////////////	  
	  
	  public static long SmallestPrimeDivisor(long n) 
	  { 
	      // if divisible by 2 
	      if (n % 2 == 0) 
	          return 2; 
	    
	      // iterate from 3 to sqrt(n) 
	      for (long i = 3; i * i <= n; i += 2) { 
	          if (n % i == 0) 
	              return i; 
	      } 
	    
	      return n; 
	  } 
	    
////////////////////	  
	   
	   public static boolean isprime(long n)
	    {
	        int count=0;
	     
	        for(long i=2;i*i<=n;i++)
	        {
	            if(n%i==0)
	            {
	                return(false);
	            }
	        }
	        return(true);
	    }
	
	   
//////////////////////
	   
	     //   (x^n)%1000000007
	   public static long modularExponentiation(long x,long n,long M)
	   {
	       if(n==0)
	           return 1;
	       else if(n%2 == 0)        //n is even
	           return modularExponentiation((x*x)%M,n/2,M);
	       else                             //n is odd
	           return (x*modularExponentiation((x*x)%M,(n-1)/2,M))%M;

	   }
	   
	   public static long nCr(int n,int k)
	   {
		  if(k==0)
			  return 1;
		  return(n*nCr(n-1,k-1)/k);
	   }
	   public static long factorial(int n)
	   {
		   if(n==1)
			   return 1;
		   return((n)*factorial(n-1));
	   }
	   
	   public static void debug(Object...o) {
		    System.out.println( Arrays.deepToString(o) );
	   }
	   
	   public static boolean prime[]=new boolean[100005];
	   //prime[j]==false means it's a prime.
	   public static void seive()
	   {
		   prime[0]=false;
		   prime[1]=false;
		   for(int i=2;i*i<=100005;i++)
		   {
			   if(!prime[i])
			   {
				   for(int j=i*i;i<=100005;j+=i)
				   {
					   prime[j]=true;
				   }
			   }
		   }
	   }
	 
	 
	    public static boolean equals(StringBuilder sb1, StringBuilder sb2){
	    
	        if(sb1 == sb2)
	  
	        if(sb1 == null || sb2 == null)
	            return false;
	        
	        boolean isEqual = true;
	  
	        if(sb1.length() == sb2.length()){
	  
	            for(int i = 0 ; i < sb1.length(); i++){
	                
	                if(sb1.charAt(i) != sb2.charAt(i)){
	                    isEqual = false;
	                    break;
	                }
	            }
	            
	        }else{
	            isEqual = false;
	        }
	        
	        return isEqual;
	    }
	   
	    
	    public static boolean IsPalindrome(String s,int n)
	    {
	    	
	    	for(int i=0;i<n/2;i++)
	    	{
	    		if(s.charAt(i)!=s.charAt(n-i-1))
	    		{
	    			return false;
	    		}
	    	}
	    	return true;
	    }
	   
	   
	    
	    static long findSubarraySum(int arr[], int n, long sum)  
	    { 
	        HashMap <Long, Integer> prevSum = new HashMap<>(); 
	        HashMap <Long ,Integer> index=new HashMap();
	        
	        long res = 0;  
	        
	        // Sum of elements so far.  
	        long currsum = 0;  
	        
	        for (int i = 0; i < n; i++) {  
	        
	            // Add current element to sum so far.  
	            currsum += arr[i];  
	            if (currsum == sum)   
	                res++;          
	        
	           
	            if (prevSum.containsKey(currsum - sum))   
	                res += prevSum.get(currsum - sum);  
	                
	         
	            Integer count = prevSum.get(currsum); 
	            if (count == null) 
	            {
	                prevSum.put(currsum, 1); 
	                index.put(currsum,i);
	            }
	                
	            else
	            {
	                prevSum.put(currsum, count+1); 
	            }
	        }  
	        
	        return res;  
	    }  
	      
	   
	   
	    
		public static void main(String []args) throws Exception
		{
			
			
			 FastReader in =new FastReader();	
			 PrintWriter pw = new PrintWriter(System.out);
		    //Scanner sc=new Scanner(System.in)
			
			char c[]=in.nextLine().toCharArray();	
			int n=c.length;
			int a[]=new int[3];
			int count=0;
			for(int i=0;i<n;i++)
			{
				a[(c[i]-'0')%3]++;
				if(a[0]>0)
				{
					count++;
					a[0]=a[1]=a[2]=0;
				}
				else
				{
					if(a[1]>0 && a[2]>0)
					{
						count++;
						a[0]=a[1]=a[2]=0;
					}
					else
					{
						if(a[1]>2 || a[2]>2)
						{
							count++;
							a[0]=a[1]=a[2]=0;

						}
					}
				}
			}
			pw.println(count);
			
			
			pw.flush();
			pw.close();
			 
		}
			
	}