						                                import java.io.BufferedReader;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.PrintWriter;
	import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
	import java.util.InputMismatchException;
				 
				 
				 
				 
				 
				public class Solution1 implements Runnable
				{
				    static final long MAX = 464897L;
				    static class InputReader
				    {
				        private InputStream stream;
				        private byte[] buf = new byte[1024];
				        private int curChar;
				        private int numChars;
				        private SpaceCharFilter filter;
				        private BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
				 
				        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 String nextLine()
				        {
				            String str = "";
				            try
				            {
				                str = br.readLine();
				            }
				            catch (IOException e)
				            {
				                e.printStackTrace();
				            }
				            return str;
				        }
				        public int nextInt()
				        {
				            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 long nextLong() 
				        {
				            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 double nextDouble() 
				        {
				            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, nextInt());
				                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, nextInt());
				                    if (c < '0' || c > '9')
				                        throw new InputMismatchException();
				                    m /= 10;
				                    res += (c - '0') * m;
				                    c = read();
				                }
				            }
				            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 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);
				        }
				    }
				     
				    public static void main(String args[]) throws Exception
				    {
				        new Thread(null, new Solution1(),"Solution",1<<26).start();
				    }   
				    static long gcd(long a, long b) 
				    { 
				      if (b == 0) 
				        return a; 
				      return gcd(b, a % b);  
				    } 
				    static long lcm(long a,long b) {
				    	return (a*b)/gcd(a,b);
				    }
				    long MOD = 1000000007;
				    long prime = 29;
				    ArrayList<Integer> adj[];
				    public void run() 
				    {
				    	InputReader sc = new InputReader(System.in);
						PrintWriter w = new PrintWriter(System.out);
						int n = sc.nextInt();
						int a = sc.nextInt();
						int b = sc.nextInt();
						int t = sc.nextInt();
						String s = sc.next();
						dp = new int[n];
						rec(s,0,t,0,a,b);
						w.println(max);
						w.close();
				    }
				    int[] dp;
				    int max = Integer.MIN_VALUE;
				    void rec(String s,int ind,int time,int count,int a,int b) {
				    	if(dp[ind] == 2) {
				    		max = Math.max(max,count);
				    		return;
				    	}
				    	dp[ind]++;
				    	int temp = 0;
				    	if(dp[ind] == 2) {
				    		time = time - a;
				    		temp--;
				    	}else {
				    		time = time - 1;
				    		if(s.charAt(ind) == 'w') {
				    			time = time - b;
				    		}
				    	}
				    	if(time < 0) {
				    		max = Math.max(max,count);
				    		return;
				    	}
				    	time = time - a;
				    	if(time < 0) {
				    		max = Math.max(max,count + 1 + temp);
				    		return;
				    	}
				    	if(ind - 1 == -1) {
				    		rec(s,s.length()-1,time,count+1+temp,a,b);
				    	}else {
				    		rec(s,ind-1,time,count+1+temp,a,b);
				    	}
				    	if(ind + 1 == s.length()) {
				    		rec(s,0,time,count+1+temp,a,b);
				    	}else {
				    		rec(s,ind+1,time,count+1+temp,a,b);
				    	}
				    	dp[ind]--;
				    }
				    double fun(double a,double b,double c) {
				    	return (a * (b + c))/(b + 2*c);
				    }
				    long[] fact = new long[100005];	
				    long nCr(int n,int r){ 
				    	long tmp1 = (fact[r] * fact[n-r]) % MOD;
				    	tmp1 = power(tmp1,MOD-2,MOD);
				    	long tmp2 = (fact[n] * tmp1) % MOD;
				    	return tmp2;
	 			    }
				    static long power(long a,long b,long mod) {
						long ans = 1;
						a = a % mod;
						while(b != 0) {
							if(b % 2 == 1) {
								ans = (ans * a) % mod;
							}
							a = (a * a) % mod;
							b = b/2;
						}
						return ans;
					}
				   void pre() {
					   fact[0] = 1;
					   for(int i = 1;i < 100005;i++) {
						   fact[i] = (fact[i-1] * i) % MOD;
					   }
				   }
				    class Pair implements Comparable<Pair>{
				        int a;
				        int b;
				        int c;
				        Pair(int a,int b,int c){
				            this.b = b;
				            this.a = a;
				            this.c = c;
				        }
				        public boolean equals(Object o) {
				            Pair p = (Pair)o;
				            return this.a == p.a && this.b == this.b;
				        }
				        public int hashCode(){
				            return Long.hashCode(a)*27 + Long.hashCode(b)*31;
				        }
				        public int compareTo(Pair p) {
				        	if(this.a == p.a) {
				        		return Integer.compare(p.b,this.b);
				        	}
				            return Long.compare(this.a,p.a);
				        }
				    }
				    
				}
