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) {
        // Return the number of games you can buy
        int count=0;
        int count1=0,count2=0;
        int money=0;
        int sum=0;
        for(int i=p;i>=6;i=i-d){
            
            
            
            
            sum+=i;
            
            
            count1++;
            
            
            
        }
        money=s-sum;
        
        
        
       while(true){
           
           if(money>6){
               money=money-6;
               count2++;
           }
           
           else break;
           
           
       }
        
       
        
        count=count1+count2;
        
        
        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();
    }
}