import java.util.*;

public class First {
    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 count = 0;
        int sum = 0;
        int temp = p;
        
        for(int i=0; ; i++) {
            sum += temp;
            p -= d;
            if(sum > s) {
                break;
            } else {
                count++;
            }
            if(p < m) {
                temp = m;
            } else {
                temp = p;
            }
        }
        
        System.out.println(count);
    }
}