import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static int howManyGames(int p, int d, int m, int s) {//20,3,6,80
        int count = 0;
        while(s>=m){ // 80>=6 , 60>=6
            if(count == 0){ //0,1
                s = s-p; //60
                count++; //1
            }
            else{
                p = p-d; //p = 17
                s = s-p; //
                count++;
            }
        }
        return count;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int p = in.nextInt();
        int d = in.nextInt();
        int m = in.nextInt();
        int s = in.nextInt();
        int answer = howManyGames(p, d, m, s);
        System.out.println(answer);
        in.close();
    }
}