Vasya's telephone contains n photos. Photo number 1 is currently opened on the phone. It is allowed to move left and right to the adjacent photo by swiping finger over the screen. If you swipe left from the first photo, you reach photo n. Similarly, by swiping right from the last photo you reach photo 1. It takes a seconds to swipe from photo to adjacent.

For each photo it is known which orientation is intended for it — horizontal or vertical. Phone is in the vertical orientation and can't be rotated. It takes b second to change orientation of the photo.

Vasya has T seconds to watch photos. He want to watch as many photos as possible. If Vasya opens the photo for the first time, he spends 1 second to notice all details in it. If photo is in the wrong orientation, he spends b seconds on rotating it before watching it. If Vasya has already opened the photo, he just skips it (so he doesn't spend any time for watching it or for changing its orientation). It is not allowed to skip unseen photos.

Help Vasya find the maximum number of photos he is able to watch during T seconds.

Input

The first line of the input contains 4 integers n, a, b, T (1 ≤ n ≤ 5·105, 1 ≤ a, b ≤ 1000, 1 ≤ T ≤ 109) — the number of photos, time to move from a photo to adjacent, time to change orientation of a photo and time Vasya can spend for watching photo.

Second line of the input contains a string of length n containing symbols 'w' and 'h'. 

If the i-th position of a string contains 'w', then the photo i should be seen in the horizontal orientation.

If the i-th position of a string contains 'h', then the photo i should be seen in vertical orientation.

Output

Output the only integer, the maximum number of photos Vasya is able to watch during those T seconds.

Examples

Input

4 2 3 10
wwhw


Output

2


Input

5 2 4 13
hhwhh


Output

4


Input

5 2 4 1000
hhwhh


Output

5


Input

3 1 100 10
whw


Output

0

Note

In the first sample test you can rotate the first photo (3 seconds), watch the first photo (1 seconds), move left (2 second), rotate fourth photo (3 seconds), watch fourth photo (1 second). The whole process takes exactly 10 seconds.

Note that in the last sample test the time is not enough even to watch the first photo, also you can't skip it.


import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java.lang.*;


public class Fourth{
	static long mod=1000000007;
	public static int lower_bound(long[] arr,int key) {
        int len = arr.length;
        int lo = 0;
        int hi = len-1;
        int mid = (lo + hi)/2;
        while (true) {
            long cmp = arr[mid]-key;
            if (cmp == 0 || cmp > 0) {
                hi = mid-1;
                if (hi < lo)
                    return mid;
            } else {
                lo = mid+1;
                if (hi < lo)
                    return mid<len-1?mid+1:-1;
            }
            mid = (lo + hi)/2;
        }
    }
    public static void main(String[] args) throws Exception{           	
    	 InputReader in = new InputReader(System.in);       
    	PrintWriter pw=new PrintWriter(System.out);   
    
    	//int t=in.readInt();
        //	while(t-->0)
        	//{
        	int n=in.readInt();
        	int a=in.readInt();
        	int b=in.readInt();
        	//int t=in.readInt();
        	
    	long t=in.readLong();
    	/*int a[]=new int[n];
    	for(int i=0;i<n;i++)
    	{
    		a[i]=in.readInt();
    	}*/
    	long ans=0;
    	long s1[]=new long[n];
        long s2[]=new long[n];
        long[] dp1=new long[n];
        long[] dp2=new long[n];
    	String a1=in.readString();
    	char c[]=a1.toCharArray();
    	long max=0;
       /* long dp1[][]=new long[n][2];
        long dp2[][]=new long[n][2];
        long dp[][]=new long[n][2];
        
    	
    	for(int i=0;i<n;i++)
    	{
    		if(i==0)
    		{
    			long e=1;   			
    			if(c[i]=='w')
    				e+=b;
    			dp1[i][0]=e;
    			if(dp1[i][0]<=t)
    			dp1[i][1]=1;
    			
    		}
    		else
    		{
    			long e=1+a;   			
    			if(c[i]=='w')
    				e+=b;
    			dp1[i][0]=dp1[i-1][0]+e;
    			if(dp1[i][0]<=t)
        			dp1[i][1]=dp1[i-1][1]+1;
    			else
    				dp1[i][1]=dp1[i-1][1];
    			//else
    				//break;
    			s1+=e;
    		}
    	}
    	
			long x=1;   			
			if(c[0]=='w')
				x+=b;
			dp2[0][0]=x;
			if(dp2[0][0]<=t)
			dp2[0][1]=1;
			s2+=x;
    	for(int i=n-1;i>0;i--)
    	{
    		if(i==n-1)
    		{
    			long e=1+a;   			
    			if(c[i]=='w')
    				e+=b;
    			dp2[i][0]=dp2[0][0]+e;
    			if(dp2[i][0]<=t)
        			dp2[i][1]=dp2[0][1]+1;
    			else
    				dp2[i][1]=dp2[0][1];
    			s2+=e;
    		}
    		else
    		{
    			long e=1+a;   			
    			if(c[i]=='w')
    				e+=b;
    			dp2[i][0]=dp2[i+1][0]+e;
    			if(dp2[i][0]<=t)
        			dp2[i][1]=dp2[i+1][1]+1;
    			else
    				dp2[i][1]=dp2[0][1];
    			s2+=e;
    		}
    	}
    	if(x<=t)
    	{
    		ans++;
    	for(int i=1;i<n;i++)
    	{
    		long y=dp1[0][i];
    		
    	}
    	}*/
    	   long[] dp=new long[n];
           for(int i=0;i<n;i++)
           {
               if(c[i]=='h')
               {
                   dp[i]=1;
               }
               else
               {
                   dp[i]=b+1;
               }
           }
     
           dp1[0]=dp[0];
           dp2[n-1]=dp[n-1];
           for(int i=n-2;i>0;i--)
           {
               dp2[i]=dp2[i+1]+dp[i];
           }
           for(int i=1;i<n;i++)
           {
               dp1[i]=dp1[i-1]+dp[i];
           }
          
           
           for(int i=0;i<n;i++)
           {
               ans=(long)(i*a)+dp1[i];
               int  r=n-1;
               int  l=i+1;
              
               int f=-1;
               
               while(l<=r)
               {
                   int mid=(l+r)/2;
                   if(l==r || r==l+1)
                   {
                	   int pos=min(i, n-l);
                       if(dp2[l]+ans+(long)pos*a+(long)(n-l)*a<=t)
                       {
                       f=l;
                       break;
                       }
                       int pos2=min(i, n-r);
                       if(dp2[r]+ans+pos2*a+(n-r)*a<=t)
                       {
                    	   
                           f=r;
                           break;
                       }
                       break;
                   }
                   if(dp2[mid]+ans+min(i,n-mid)*a+(n-mid)*a<=t)
                   {
                       f=mid;
                       r=mid-1;
                   }
                   else
                   {
                       l=mid+1;
                   }
                   
                   
               }
               if(ans<=t)
               {
                   max=max(max, i+1);
                   if(f!=-1)
                   {
                      
                       max=max(max, i+1+n-f);
                   }
               }
               
           }
           pw.println(max);

		  // pw.println(ans);	     	
    	
    	//}
    	    		
    	
    	pw.close();
    }
    
   
    public static BigInteger fact(int n)
    {
    	BigInteger x=BigInteger.valueOf(1);
    	for(int i=1;i<=n;i++)
    	{
    		x=x.multiply(BigInteger.valueOf(i));
    	}
    	return x;
    }
    /* returns nCr mod m */
   	public static long comb(long n, long r, long m) 
   	{
   		long p1 = 1, p2 = 1;
   		for (long i = r + 1; i <= n; i++) {
   			p1 = (p1 * i) % m;
   		}
   		p2 = factMod(n - r, m);
   		p1 = divMod(p1, p2, m);
   		return p1 % m;
   	}
   /* returns a/b mod m, works only if m is prime and b divides a */
   	public static long divMod(long a, long b, long m) 
   	{
   		long c = powerMod(b, m - 2, m);
   		return ((a % m) * (c % m)) % m;
   	}
   /* calculates factorial(n) mod m */
   	public static long factMod(long n, long m) {
   		long result = 1;
   		if (n <= 1)
   			return 1;
   		while (n != 1) {
   			result = ((result * n--) % m);
   		}
   		return result;
   	}
   /* This method takes a, b and c as inputs and returns (a ^ b) mod c */
   	public static long powerMod(long a, long b, long c) {
   		long result = 1;
   		long temp = 1;
   		long mask = 1;
   		for (int i = 0; i < 64; i++) {
   			mask = (i == 0) ? 1 : (mask * 2);
   			temp = (i == 0) ? (a % c) : (temp * temp) % c;
   			/* Check if (i + 1)th bit of power b is set */
   			if ((b & mask) == mask) {
   				result = (result * temp) % c;
   			}
   		}
   		return result;
   	}
	static boolean isPrime(int number) {
        if (number <= 1) {
            return false;
        }
        if (number <= 3) {
            return true;
        }
        if (number % 2 == 0 || number % 3 == 0) {
            return false;
        }
        int i = 5;
        while (i * i <= number) {
            if (number % i == 0 || number % (i + 2) == 0) {
                return false;
            }
            i += 6;
        }
        return true;
    }
	
public static long gcd(long x,long y)
{
	if(x%y==0)
		return y;
	else
		return gcd(y,x%y);
}
	
public static int gcd(int x,int y)
{
	if(x%y==0)
		return y;
	else 
		return gcd(y,x%y);
}
public static int abs(int a,int b)
{
	return (int)Math.abs(a-b);
}
public static long abs(long a,long b)
{
	return (long)Math.abs(a-b);
}
public static int max(int a,int b)
{
	if(a>b)
		return a;
	else
		return b;
}
public static int min(int a,int b)
{
	if(a>b)
		return b;
	else 
		return a;
}
public static long max(long a,long b)
{
	if(a>b)
		return a;
	else
		return b;
}
public static long min(long a,long b)
{
	if(a>b)
		return b;
	else 
		return a;
}

static boolean isPowerOfTwo (long v) {
	return (v & (v - 1)) == 0;
}
public static long pow(long n,long p,long m)
{
	 long  result = 1;
	  if(p==0)
	    return 1;
	if (p==1)
	    return n;
	while(p!=0)
	{
	    if(p%2==1)
	        result *= n;
	    if(result>=m)
	    result%=m;
	    p >>=1;
	    n*=n;
	    if(n>=m)
	    n%=m;
	}
	return result;
}
public static long pow(long n,long p)
{
	long  result = 1;
	  if(p==0)
	    return 1;
	if (p==1)
	    return n;
	while(p!=0)
	{
	    if(p%2==1)
	        result *= n;	    
	    p >>=1;
	    n*=n;	    
	}
	return result;

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

	public int compareTo(Pair o) {
		// TODO Auto-generated method stub
		if(this.a!=o.a)
		return Integer.compare(this.a,o.a);
		else
			return Integer.compare(this.b, o.b);
		//return 0;
	}
	public boolean equals(Object o) {
        if (o instanceof Pair) {
            Pair p = (Pair)o;
            return p.a == a && p.b == b;
        }
        return false;
    }
    public int hashCode() {
        return new Integer(a).hashCode() * 31 + new Integer(b).hashCode();
    }
} 
    
static long sort(int a[],int n)
{  	int b[]=new int[n];	
	return mergeSort(a,b,0,n-1);}
static long mergeSort(int a[],int b[],long left,long right)
{ long c=0;if(left<right)
 {   long mid=left+(right-left)/2;
	 c= mergeSort(a,b,left,mid);
	 c+=mergeSort(a,b,mid+1,right);
	 c+=merge(a,b,left,mid+1,right); }	
	return c;	 }
static long merge(int a[],int  b[],long left,long mid,long right)
{long c=0;int i=(int)left;int j=(int)mid; int k=(int)left;
while(i<=(int)mid-1&&j<=(int)right)
{ if(a[i]<=a[j]) {b[k++]=a[i++]; }
else	{ b[k++]=a[j++];c+=mid-i;}}
while (i <= (int)mid - 1)   b[k++] = a[i++]; 
while (j <= (int)right) b[k++] = a[j++];
for (i=(int)left; i <= (int)right; i++) 
	a[i] = b[i];  return c;  }
    
    
   static  class InputReader
    {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream)
        {
            this.stream = stream;
        }

        public int read()
        {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars)
            {
                curChar = 0;
                try
                {
                    numChars = stream.read(buf);
                } catch (IOException e)
                {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int readInt()
        {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-')
            {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do
            {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString()
        {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do
            {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }
        public double readDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, readInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, readInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
        public long readLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
        public boolean isSpaceChar(int c)
        {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next()
        {
            return readString();
        }

        public interface SpaceCharFilter
        {
            public boolean isSpaceChar(int ch);
        }
    }

     static class OutputWriter
    {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream)
        {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer)
        {
            this.writer = new PrintWriter(writer);
        }

        public void print(Object... objects)
        {
            for (int i = 0; i < objects.length; i++)
            {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }

        public void printLine(Object... objects)
        {
            print(objects);
            writer.println();
        }

        public void close()
        {
            writer.close();
        }

        public void flush()
        {
            writer.flush();
        }

    }
    /* USAGE

    //initialize
        InputReader in 		= new InputReader(System.in);
        OutputWriter out	=	new OutputWriter(System.out);

    //read int
    int i = in.readInt();
    //read string
    String s = in.readString();
    //read int array of size N
    int[] x = IOUtils.readIntArray(in,N);
    //printline
    out.printLine("X");


    //flush output
    out.flush();

    //remember to close the
    //outputstream, at the end
    out.close();

    */
  static   class IOUtils {

        public static int[] readIntArray(InputReader in, int size) {
            int[] array = new int[size];
            for (int i = 0; i < size; i++)
                array[i] = in.readInt();
            return array;
    }
    }
//BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	//StringBuilder sb=new StringBuilder("");
	 //InputReader in = new InputReader(System.in);
  // OutputWriter out = new OutputWriter(System.out);
	//PrintWriter pw=new PrintWriter(System.out);
	//String line=br.readLine().trim();
	       	
	//int t=Integer.parseInt(br.readLine());
  //	while(t-->0)
  	//{
  	//int n=Integer.parseInt(br.readLine());
	//long n=Long.parseLong(br.readLine());
	//String l[]=br.readLine().split(" ");
  //int m=Integer.parseInt(l[0]);
	//int k=Integer.parseInt(l[1]);
	//String l[]=br.readLine().split(" ");
	//l=br.readLine().split(" ");
	/*int a[]=new int[n];
	for(int i=0;i<n;i++)
	{
		a[i]=Integer.parseInt(l[i]);
	}*/
	   //System.out.println(" ");	     	
	
	//}
}