#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int p,d,s,m,ans;
int main() {
    cin>>p>>d>>m>>s;
    while(true)
    {
       s-=p;
if(s>=0)
    ans++;
        if(p-d>=m)
            p-=d;
        else
            p=m;
        if(s<=0)
            break;
    }
    cout<<ans<<endl;
    return 0;
}