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


int main() {
    int d,p,m,s;
    cin>>p>>d>>m>>s;
    int c=0;
    while(1)
    {
        if(s<p)
            break;
        else
        {
            c++;
            s-=p;
            if(p-d>=m)
            p=p-d;
            else
                p=m;
                
        }
    }
    cout<<c;
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}