package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"
)

func readInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	return n
}

func read(s *bufio.Scanner) (int, int, int, int) {
	return readInt(s),
		readInt(s),
		readInt(s),
		readInt(s)
}

func compute(p, d, m, s int) int {

	result := 0
	for {

		if s-p < 0 {
			break
		}

		result++

		s -= p
		p -= d
		if p < m {
			p = m
		}

	}

	return result
}

func run(in io.Reader, out io.Writer) {

	s := bufio.NewScanner(in)
	s.Split(bufio.ScanWords)

	p, d, m, ss := read(s)
	result := compute(p, d, m, ss)
	fmt.Fprint(out, result)
}

func main() {
	run(os.Stdin, os.Stdout)
}