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:
/* 
 * UMANG PANCHAL
 * DAIICT
 */

import java.util.*;
import java.io.*;
import java.math.*;
import java.util.Comparator;
public class Main
{
 
	private static final Comparator<? super Integer> Comparator = null;
	static LinkedList<Integer> adj[];
	static ArrayList<Integer> adj1[];
	static int[] color,visited1;
	static boolean b[],visited[],possible;
	static int level[];
	static Map<Integer,HashSet<Integer>> s;
	static int totalnodes,colored;
	static int count[];
	static long sum[];
	static int nodes;
	static long ans=0;
	static long[] as=new long[10001];
	static long c1=0,c2=0;
	static int[] a,d,k;
	static int max=100000000;
	static long MOD = 1000000007,sm=0,m=Long.MIN_VALUE;
	static boolean[] prime=new boolean[1000005];
	static int[] levl;
    static int[] eat;
    static int price[];
    static int res[],par[],co[];
    static int result=0;
    static int[] root,size,du,dv;
    static long p=Long.MAX_VALUE;
    static int start,end,r=0;
    static boolean[] vis1,vis2;
    static int to;
    static HashMap<Pair,Integer> hs;
    static boolean ns;
    static Node head;
    static String st,t;
    static long n;
  
	// --------------------My Code Starts Here----------------------
	
	public static void main(String[] args) throws IOException
	{
		in=new InputReader(System.in);
	    w=new PrintWriter(System.out);
	    
	     String s=ns();
	     int[] a=new int[s.length()];
	     for(int i=0;i<s.length();i++)
	    	 a[i]=(s.charAt(i)-'0')%3;
	     
	     
	     int ans=0;
	     int sum=0;
	     int o=0,t=0;
	     for(int i=0;i<s.length();i++)
	     {
	    	  if(a[i]==0)
	    	  {
	    		  ans++;
	    		  sum=0;  
	    		  t=0;
	    		  o=0;
	    	  }
	    	  else
	    	  {
	    		  if(a[i]==2)
	    		  {
	    			  if(o!=0 || t>=2)
	    			  {
	    				  ans++;
	    			      o=0;
	    			      t=0;
	    			  }
	    			  else
	    				  t++;
	    		  }
	    		  else if(a[i]==1)
	    		  {
	    			  if(t!=0 || o>=2)
	    			  {
	    				  ans++;
	    				  t=0;
	    				  o=0;
	    			  }
	    			  else
	    				  o++;
	    			  
	    		  }
	    	  }
	     }
	    w.print(ans);
       w.close();
	}

	
	
	
	// --------------------My Code Ends Here------------------------
  
	static class Pair implements Comparable<Pair>
	 {
		Integer a;
		Integer b;
		
	     
	        Pair(int a,int b)
	        {
	            this.a=a;
	            this.b=b;
	            //this.l=l;
	     
	        }
	        public int compareTo(Pair p)
	        {
	        	if(this.a==p.a)
	        	   return Long.compare(this.b,p.b);
	        	else
	        		return Long.compare(this.a,p.a);
	        }
		
	}
	public static long setBit(long n)
	    {
	 
	        // To find the position of the
	        // most significant set bit
	        long k = (long)(Math.log(n) / Math.log(2));
	 
	        // To return the the value of the number
	        // with set bit at k-th position
	        return (long)(Math.pow(2, k));
	    }
	public static void swap(int[] a,int l,int r)
	{
		int t=a[l];
		a[l]=a[r];
		a[r]=t;
	}
	public static void sort(long[] a)
	{
	   ArrayList<Long> al=new ArrayList<Long>();
	   for(int i=0;i<a.length;i++)
		   al.add(a[i]);
	   Collections.sort(al);
	   for(int i=0;i<a.length;i++)
		   a[i]=al.get(i);
	}
	public static void dfs(int n,boolean[] vis,int cl,int[] c)
	{
	
		vis[n]=true;
		if(c[n]!=cl)
			ns=false;
		for(int i:adj[n])
		{
			if(!vis[i])
			{
				 dfs(i,vis,cl,c);
			}
		}
		
	}

	static long pow(long a, long b, long c) {
		if (b == 0)
			return 1;
		long p = pow(a, b / 2, c);
		p = (p * p) % c;
		return (b % 2 == 0) ? p : (a * p) % c;
	}
	
	public static long kadane(long[] a,int n)
	{
		 long max_here=0,max_so_far=-Long.MAX_VALUE;
	        for(int i=0;i<n;i++)
	        {
	        	 if(max_here<0)
	                   max_here=0;
	        	
	        	 max_here+=a[i];
	          
	             
	      
	           if(max_here>max_so_far)
	                    max_so_far=max_here;
	          
	                  
	        }
		return max_so_far;
	}
	public static class SegmentTreeRMQ
	{
	    int st[]; //array to store segment tree
	 
	    // A utility function to get minimum of two numbers
	    int minVal(int x, int y) {
	        return (x < y) ? y : x;
	    }
	 
	    // A utility function to get the middle index from corner
	    // indexes.
	    int getMid(int s, int e) {
	        return s + (e - s) / 2;
	    }
	 
	    /*  A recursive function to get the minimum value in a given
	        range of array indexes. The following are parameters for
	        this function.
	 
	        st    --> Pointer to segment tree
	        index --> Index of current node in the segment tree. Initially
	                   0 is passed as root is always at index 0
	        ss & se  --> Starting and ending indexes of the segment
	                     represented by current node, i.e., st[index]
	        qs & qe  --> Starting and ending indexes of query range */
	    int RMQUtil(int ss, int se, int qs, int qe, int index)
	    {
	        // If segment of this node is a part of given range, then
	        // return the min of the segment
	        if (qs <= ss && qe >= se)
	            return st[index];
	 
	        // If segment of this node is outside the given range
	        if (se < qs || ss > qe)
	            return Integer.MIN_VALUE;
	 
	        // If a part of this segment overlaps with the given range
	        int mid = getMid(ss, se);
	        return minVal(RMQUtil(ss, mid, qs, qe, 2 * index + 1),
	                RMQUtil(mid + 1, se, qs, qe, 2 * index + 2));
	    }
	 
	    // Return minimum of elements in range from index qs (quey
	    // start) to qe (query end).  It mainly uses RMQUtil()
	    int RMQ(int n, int qs, int qe)
	    {
	        // Check for erroneous input values
	        if (qs < 0 || qe > n-1 || qs > qe) {
	            System.out.println("Invalid Input");
	            return 1;
	        }
	 
	        return RMQUtil(0, n - 1, qs, qe, 0);
	    }
	 
	    // A recursive function that constructs Segment Tree for
	    // array[ss..se]. si is index of current node in segment tree st
	    int constructSTUtil(int arr[], int ss, int se, int si)
	    {
	        // If there is one element in array, store it in current
	        //  node of segment tree and return
	        if (ss == se) {
	            st[si] = arr[ss];
	            return arr[ss];
	        }
	 
	        // If there are more than one elements, then recur for left and
	        // right subtrees and store the minimum of two values in this node
	        int mid = getMid(ss, se);
	        st[si] = minVal(constructSTUtil(arr, ss, mid, si * 2 + 1),
	                constructSTUtil(arr, mid + 1, se, si * 2 + 2));
	        return st[si];
	    }
	 
	    /* Function to construct segment tree from given array. This function
	       allocates memory for segment tree and calls constructSTUtil() to
	       fill the allocated memory */
	    void constructST(int arr[], int n)
	    {
	        // Allocate memory for segment tree
	 
	        //Height of segment tree
	        int x = (int) (Math.ceil(Math.log(n) / Math.log(2)));
	 
	        //Maximum size of segment tree
	        int max_size = 2 * (int) Math.pow(2, x) - 1;
	        st = new int[max_size]; // allocate memory
	 
	        // Fill the allocated memory st
	        constructSTUtil(arr, 0, n - 1, 0);
	    }
	 
	    // Driver program to test above functions
	
	}
	
	public static int fact(int n)
	{
		HashMap<Integer,Integer> hm=new HashMap<Integer,Integer>();
		boolean ans=true;
		 while (n%2==0)
	        {
	            if(hm.containsKey(2))
	            {	hm.put(2,hm.get(2)+1);
	            ans=false;
	            }
	            else
	            	hm.put(2,1);
	            n /= 2;
	        }
	 
	        // n must be odd at this point.  So we can
	        // skip one element (Note i = i +2)
	        for (int i = 3; i <= Math.sqrt(n); i+= 2)
	        {
	            // While i divides n, print i and divide n
	            while (n%i == 0)
	            {
	            	  if(hm.containsKey(i))
	  	            	{hm.put(i,hm.get(i)+1);
	  	            	ans=false;
	  	            	}
	  	            else
	  	            	hm.put(i,1);
	                n /= i;
	            }
	        }
	 
	        // This condition is to handle the case whien
	        // n is a prime number greater than 2
	        if (n > 2)
	        	 if(hm.containsKey(n))
	  	            	{hm.put(n,hm.get(n)+1);
	  	            	ans=false;
	  	            	}
	  	            else
	  	            	hm.put(n,1);
		if(ans)
			return hm.size();
		else
			return -1;
	}
	public static int binary_search(long[] a,long k,int l,int r)
	{
		
		while(l<=r)
		{
			int mid=(l+r)/2;
			 if(a[mid]>=k)
			{
				r=mid-1;
			}
			else
				l=mid+1;
		}
		return l;
	}

	   public static void removeDuplicates()
	    {
	         Node cur=head;
	         while(cur!=null)
	         {
	        	// w.println(1);
	             int k=cur.data;
	             Node p=cur.next;
	             Node pre=cur;
	             while(p!=null)
	             {
	            	// w.println(2);
	                 if(p.data==k)
	                 {
	                     pre.next=p.next;
	                     p=pre.next;
	                 }
	                 else
	                 {
	                     p=p.next;
	                     pre=pre.next;
	                 }
	             }
	             cur=cur.next;
	         }
	     
	    }

	public static void insert_front(int x)
	{
		Node f=new Node(x);
		f.next=head;
		head=f;
	}
	public static void insert_mid(Node x,int d)
	{
		if(x==null)
		{
			w.println("Nothing can be shown");
			return;
		}
		Node nex=x.next;
		Node ne=new Node(d);
		x.next=ne;
		ne.next=nex;
	}
	public static void insert_end(int x)
	{
		Node f=new Node(x);
		Node temp=head;
		while(temp.next!=null)
			temp=temp.next;
		temp.next=f;
			
	}
	public static class Node
	{
		int data;
		Node next;
		Node(int d)
		{
			this.data=d;
			this.next=null;
		}
	}


     

	
	
	/*
	 *  PriorityQueue<Integer> pq = new PriorityQueue<Integer>(new Comparator<Integer>()
  			{
  				public int compare(Integer o1, Integer o2)
  				{
  					return Intege
  					r.compare(o2,o1);
  				}
  			});
	 * 
	 * 
	 */
	
	public static void shuffle(long[] a,int n)
	{
		Random r=new Random();
		for(int i=n-1;i>0;i--)
		{
			int j=r.nextInt(i);
			long t=a[j];
			a[j]=a[i];
			a[i]=t;
		}
	}
	public static void bfs1(int u)
	{
	    Queue<Integer> q=new LinkedList();
	    q.add(u);
	    visited[u]=true;
	    while(!q.isEmpty())
	    {
	    	//w.print(1);
	    	int p=q.poll();
	      for(int i=0;i<adj[p].size();i++)
	     { 
	    	  if(!visited[adj[p].get(i)])
	    	  {
	    	q.add(adj[p].get(i));
	    	visited[adj[p].get(i)]=true;
	    	  }
	    	  levl[adj[p].get(i)]=levl[p]+1;
	    	  }
	    }
	    
	}
	public static void bfs2(int u)
	{
	    Queue<Integer> q=new LinkedList();
	    q.add(u);
	    vis2[u]=true;
	    while(!q.isEmpty())
	    {
	    	int p=q.poll();
	      for(int i=0;i<adj[p].size();i++)
	     { 
	    	  if(!vis2[adj[p].get(i)])
	    	  {
	    	dv[adj[p].get(i)]=dv[p]+1;
	    	q.add(adj[p].get(i));
	    	  
	    	vis2[adj[p].get(i)]=true;
	    	  }
	    	  }
	    }
	    
	}
	 public static void buildgraph(int n)
	 {
         adj=new LinkedList[n+1];
         visited=new boolean[n];
         level=new int[n];
         par=new int[n];
         for(int i=0;i<=n;i++)
         	{
        	 adj[i]=new LinkedList<Integer>();
         	
         	}
      
	 }
	
	/*public static long kruskal(Pair[] p)
	{
		long ans=0;
		int w=0,x=0,y=0;
		for(int i=0;i<p.length;i++)
		{
			w=p[i].w;
			x=p[i].x;
			y=p[i].y;
			if(root(x)!=root(y))
			{
				ans+=w;
				union(x,y);
			}
		}
		return ans;
	}*/
	

	 static  class npair implements Comparable<npair>
	 {
	     int a,b;
	     
	
		npair(int a,int b)
		{
			this.a=a;
			this.b=b;
			//this.index=index;
		}


		public int compareTo(npair o) {
			// TODO Auto-generated method stub
			return Integer.compare(this.a,o.a);
		}


	
		
	}
	public static int root(int i)
	{
		while(root[i]!=i)
		{
			root[i]=root[root[i]];
			i=root[i];
		}
		return i;
	}
	
	public static void init(int n)
	{
		root=new int[n+1];
		for(int i=1;i<=n;i++)
			root[i]=i;
	}
	public static void union(int a,int b)
	{
	    int root_a=root(a);	
	    int root_b=root(b);
	    root[root_a]=root_b;
	   // size[root_b]+=size[root_a];
	}


	
	public static boolean isPrime(long n)
	{
	    // Corner cases
	    if (n <= 1)  return false;
	    if (n <= 3)  return true;
	 
	    // This is checked so that we can skip 
	    // middle five numbers in below loop
	    if (n%2 == 0 || n%3 == 0)
	    	return false;
	 
	    for (long i=5; i*i<=n; i=i+6)
	        if (n%i == 0 || n%(i+2) == 0)
	           return false;
	 
	    return true;
	}
	

	
	public static String ns()
	{
		return in.nextLine();
	}
	public static int ni()
	{
		return in.nextInt();
	}
	public static long nl()
	{
		return in.nextLong();
	}
	public static int[] na(int n)
	{
		int[] a=new int[n];
		for(int i=0;i<n;i++)
		a[i]=ni();
		return a;
	}
	public static long[] nla(int n)
	{
		long[] a=new long[n];
		for(int i=0;i<n;i++)
		a[i]=nl();
		return a;
	}
	public static void sieve()
	    {
	       int n=prime.length;
	        for(int i=0;i<n;i++)
	            prime[i] = true;
	         
	        for(int p = 2; p*p <=n; p++)
	        {
	            if(prime[p] == true)
	            {
	                for(int i = p*2; i <n; i += p)
	                    prime[i] = false;
	            }
	        }
	    }

  public static String rev(String s)
	{
		StringBuilder sb=new StringBuilder(s);
		sb.reverse();
		return sb.toString();
	}
	static long lcm(long a, long b)
	{
	    return a * (b / gcd(a, b));
	}
	static long gcd(long a, long b)
	{
	    while (b > 0)
	    {
	        long temp = b;
	        b = a % b; // % is remainder
	        a = temp;
	    }
	    return a;
	}
	static InputReader in;
	static PrintWriter w;
static class InputReader 
{
 
private final InputStream stream;
private final byte[] buf = new byte[8192];
private int curChar, snumChars;
private SpaceCharFilter filter;
 
public InputReader(InputStream stream)
{
  this.stream = stream;
}
 
public int snext()
{
  if (snumChars == -1)
    throw new InputMismatchException();
  if (curChar >= snumChars)
  {
    curChar = 0;
    try 
    {
      snumChars = stream.read(buf);
    }
    catch (IOException e)
    {
      throw new InputMismatchException();
    }
    if (snumChars <= 0)
      return -1;
  }
  return buf[curChar++];
}
 
public int nextInt() 
{
  int c = snext();
  while (isSpaceChar(c)) 
  {
    c = snext();
  }
  int sgn = 1;
  if (c == '-')
  {
    sgn = -1;
    c = snext();
  }
  int res = 0;
  do
  {
    if (c < '0' || c > '9')
      throw new InputMismatchException();
    res *= 10;
    res += c - '0';
    c = snext();
  }
  while (!isSpaceChar(c));
  return res * sgn;
}
 
public long nextLong() 
{
  int c = snext();
  while (isSpaceChar(c)) 
  {
    c = snext();
  }
  int sgn = 1;
  if (c == '-')
  {
    sgn = -1;
    c = snext();
  }
  long res = 0;
  do
  {
    if (c < '0' || c > '9')
      throw new InputMismatchException();
    res *= 10;
    res += c - '0';
    c = snext();
  }
  while (!isSpaceChar(c));
  return res * sgn;
}	    
public String readString() 
{
  int c = snext();
  while (isSpaceChar(c)) 
  {
    c = snext();
  }
  StringBuilder res = new StringBuilder();
  do
  {
    res.appendCodePoint(c);
    c = snext();
  }
  while (!isSpaceChar(c));
  return res.toString();
}
 
public String nextLine() 
{
  int c = snext();
  while (isSpaceChar(c))
    c = snext();
  StringBuilder res = new StringBuilder();
  do
  {
    res.appendCodePoint(c);
    c = snext();
  }
  while (!isEndOfLine(c));
  return res.toString();
}
 
public boolean isSpaceChar(int c)
{
  if (filter != null)
    return filter.isSpaceChar(c);
  return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
}
 
private boolean isEndOfLine(int c) 
{
  return c == '\n' || c == '\r' || c == -1;
}
 
public interface SpaceCharFilter
{
  public boolean isSpaceChar(int ch);
}
}
	
}