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.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.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;
                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<>();
            ArrayList<IntIntPair> other = new ArrayList<>();
            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.add(new IntIntPair(lefttime, bad.length - left));
            }
            int resres = right + (includeright ? 1 : 0);
            int otherindex = other.size() - 1;
            for(IntIntPair p : al) {
                int already = p.first + 1;
                int moartime = p.second;
                while(otherindex >= 0 && other.get(otherindex).first > moartime) otherindex--;
                int best = (otherindex == -1 ? 0 : other.get(otherindex).second);
                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 = 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);

        }

    }
}

