import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.BufferedWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.TreeMap;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Alex
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        TaskD solver = new TaskD();
        solver.solve(1, in, out);
        out.close();
    }
    static class TaskD {
        int solve(boolean[] bad, int movetime, int rotatetime, int tottime) {
            int right = 0; // not inclusive
            boolean includeright = false;
            int time = tottime;
            ArrayList<IntIntPair> al = new ArrayList<>();
            while(time >= 1 + (bad[right] ? rotatetime : 0)) {
                time -= (1 + (bad[right] ? rotatetime : 0));
                includeright = true;
//            out.printLine("TIME", right, time);
                al.add(new IntIntPair(right, time - movetime * (right + 1)));
                if(right == bad.length - 1) {
                    return bad.length;
                }
                if(time >= movetime) {
                    time -= movetime;
                    right++;
                    includeright = false;
                }
            }
            TreeMap<Integer, Integer> other = new TreeMap<>();
            int lefttime = 0;
            for(int left = bad.length - 1; left >= 0; left--) {
                if(left < bad.length - 1) lefttime += movetime;
                lefttime += (bad[left] ? rotatetime : 0);
                lefttime++;
                other.put(lefttime, bad.length - left);
            }
            int resres = right + (includeright ? 1 : 0);
//        out.printLine("HERE", right, includeright);
            for(IntIntPair p : al) {
                int already = p.first + 1;
                int moartime = p.second;
//            out.printLine(already, moartime);
                Integer bestnull = other.floorKey(moartime);
                int best = (bestnull == null ? 0 : other.get(bestnull));
                resres = Math.max(resres, already + best);
            }
            return resres;
        }

        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int numphotos = in.readInt(); // n [1, 5 * 10 ^ 5]
            int movetime = in.readInt(); // a [1, 1000]
            int rotatetime = in.readInt(); // b [1, 1000]
            int tottime = in.readInt(); // T [1, 10 ^ 9]
            char[] photos = in.next().toCharArray(); // n [1, 5 * 10 ^ 5]
            boolean[] bad = new boolean[photos.length];
            for(int i = 0; i < bad.length; i++) bad[i] = (photos[i] == 'w');
            boolean[] otherbad = new boolean[bad.length];
            otherbad = bad.clone();
            for(int i = bad.length - 1; i > 0; i--) {
                int otherindex = bad.length - i;
                if(otherindex >= i) break;
                otherbad[i] = bad[otherindex];
                otherbad[otherindex] = bad[i];
            }
            out.printLine(Math.max(solve(bad, movetime, rotatetime, tottime),
                    solve(otherbad, movetime, rotatetime, tottime)));
        }

    }

    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 close() {
            writer.close();
        }

        public void printLine(int i) {
            writer.println(i);
        }

    }

    static class IntIntPair implements Comparable<IntIntPair> {
        public final int first;
        public final int second;

        public IntIntPair(int first, int second) {
            this.first = first;
            this.second = second;
        }


        public boolean equals(Object o) {
            if(this == o) return true;
            if(o == null || getClass() != o.getClass()) return false;

            IntIntPair pair = (IntIntPair) o;

            return first == pair.first && second == pair.second;

        }


        public int hashCode() {
            int result = Integer.hashCode(first);
            result = 31 * result + Integer.hashCode(second);
            return result;
        }


        public String toString() {
            return "(" + first + "," + second + ")";
        }

        @SuppressWarnings({"unchecked"})
        public int compareTo(IntIntPair o) {
            int value = Integer.compare(first, o.first);
            if(value != 0) {
                return value;
            }
            return Integer.compare(second, o.second);
        }

    }

    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 {
                if(Character.isValidCodePoint(c))
                    res.appendCodePoint(c);
                c = read();
            } while(!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if(filter != null)
                return filter.isSpaceChar(c);
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

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

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

        }

    }
}

