#include<bits/stdc++.h>
using namespace std;
int main(){
	int m,p,d,s,cost=0,games=0;
	cin>>m>>p>>d>>s;
	while((cost+m)<=s){
		cost+=m;
		if(m-p > d)
			m-=p;
        else
            m=d;
        //cout<<cost<<" ";
		games++;
	}
	cout<<games;
}