#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int count=0;
   
    if(s<m)
    {
        cout<<0;
        return 0;
    }
    while(s>0)
    {
        if(s<m)
            break;
        s=s-p;
        if(p>m)
        {
            if((p-d)>=m)
            p=p-d;
            else
                p=m;
        }
        else
            p=m;
        if(s>=0)
        count++;
        //cout<<p<<" "<<s<<endl;
    }
    cout<<count;
    return 0;
}