//
//  main.cpp
//  1
//
//  Created by anand kumar on 09/09/17.
//  Copyright © 2017 anand kumar. All rights reserved.
//

#include <iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<map>
using namespace std;
#define ll long long

int main(int argc, const char * argv[]) {
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int coun=0;
    while(s>=p)
    {//cout<<"wh ";
        if(s>=p)
        {
            s-=p;
            coun++;
        }
        if(p-d>m)
        {
            p-=d;
        }
        else{
            p=m;
        }
        
    
    }
    cout<<coun<<endl;
}