Arthur and Alexander are number busters. Today they've got a competition. 

Arthur took a group of four integers a, b, w, x (0 ≤ b < w, 0 < x < w) and Alexander took integer с. Arthur and Alexander use distinct approaches to number bustings. Alexander is just a regular guy. Each second, he subtracts one from his number. In other words, he performs the assignment: c = c - 1. Arthur is a sophisticated guy. Each second Arthur performs a complex operation, described as follows: if b ≥ x, perform the assignment b = b - x, if b < x, then perform two consecutive assignments a = a - 1; b = w - (x - b).

You've got numbers a, b, w, x, c. Determine when Alexander gets ahead of Arthur if both guys start performing the operations at the same time. Assume that Alexander got ahead of Arthur if c ≤ a.

Input

The first line contains integers a, b, w, x, c (1 ≤ a ≤ 2·109, 1 ≤ w ≤ 1000, 0 ≤ b < w, 0 < x < w, 1 ≤ c ≤ 2·109).

Output

Print a single integer — the minimum time in seconds Alexander needs to get ahead of Arthur. You can prove that the described situation always occurs within the problem's limits.

Examples

Input

4 2 3 1 6


Output

2


Input

4 2 3 1 7


Output

4


Input

1 2 3 2 6


Output

13


Input

1 1 2 1 1


Output

0
import java.io.*;
import java.math.*;
import java.util.*;
import java.util.concurrent.ArrayBlockingQueue;



public class Main {

    InputReader input;
    PrintWriter output;

    void run(){
        output = new PrintWriter(new OutputStreamWriter(System.out));
        input = new InputReader(System.in);
        solve();
        output.flush();
    }

    public static void main(String[] args){
        new Main().run();
    }
    
    long a, b, w, x;
    long c;
    
    void solve() {
        a = input.ni();
        b = input.ni();
        w = input.ni();
        x = input.ni();
        c = input.ni();
        if(c <= a) {
            output.println("0");
            return;
        }
        findMin();
    }

    void findMin() {
        long lo = 1;
        long hi = Long.MAX_VALUE / 2;
        while(lo < hi) {
            long mid = (lo + hi)>>1;
            if(possible(mid)) {
                hi = mid;
            }
            else {
                lo = mid+1;
            }
        }
        output.println(hi);
    }
    
    boolean possible(long time) {
        long currA = a;
        long currC = c;
        long q = Math.max(x*time - b, 0);
        long numSecondOperation = (q+w-1) / w;
        currA -= numSecondOperation;
        currC -= time;
        return currA >= currC;
    }
    
    class InputReader {
        private boolean finished = false;
        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 peek() {
                if (numChars == -1)
                        return -1;
                if (curChar >= numChars) {
                        curChar = 0;
                        try {
                                numChars = stream.read(buf);
                        } catch (IOException e) {
                                return -1;
                        }
                        if (numChars <= 0)
                                return -1;
                }
                return buf[curChar];
        }

        public int ni() {
                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 nl() {
                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 String ns() {
                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 isWhitespace(c);
        }

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

        private String readLine0() {
                StringBuilder buf = new StringBuilder();
                int c = read();
                while (c != '\n' && c != -1) {
                        if (c != '\r')
                                buf.appendCodePoint(c);
                        c = read();
                }
                return buf.toString();
        }

        public String readLine() {
                String s = readLine0();
                while (s.trim().length() == 0)
                        s = readLine0();
                return s;
        }

        public String readLine(boolean ignoreEmptyLines) {
                if (ignoreEmptyLines)
                        return readLine();
                else
                        return readLine0();
        }

        public BigInteger readBigInteger() {
                try {
                        return new BigInteger(ns());
                } catch (NumberFormatException e) {
                        throw new InputMismatchException();
                }
        }

        public char readCharacter() {
                int c = read();
                while (isSpaceChar(c))
                        c = read();
                return (char) c;
        }

        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, ni());
                        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, ni());
                                if (c < '0' || c > '9')
                                        throw new InputMismatchException();
                                m /= 10;
                                res += (c - '0') * m;
                                c = read();
                        }
                }
                return res * sgn;
        }

        public boolean eof() {
                int value;
                while (isSpaceChar(value = peek()) && value != -1)
                        read();
                return value == -1;
        }

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

        public SpaceCharFilter getFilter() {
                return filter;
        }

        public void setFilter(SpaceCharFilter filter) {
                this.filter = filter;
        }
       
    }
     public interface SpaceCharFilter {
         public boolean isSpaceChar(int ch);
     }

}

