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


int main() {
    int p, d, m, s, ans=0, v;
    cin>>p>>d>>m>>s;
    v=p;
    while(s>=v){
        s-=v;
        ans++;
        if(v-d>=m) v-=d;
        else v=m;
    }
    cout<<ans<<endl;
    return 0;
}