#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 nos=0;
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    
    while(p>m && s>=p)
    {
        s-=p;
        nos++;
        p-=d;
    }
    if(p<=m && s>p)
    {
    p=m;
    nos+=s/p;
    }
    cout<<nos;
    return 0;
}