#include <iostream>
using namespace std;
int main()
{
	int p,d,m,s;
	cin>>p>>d>>m>>s;
	int count=0;
	while(s>0)
	{
	    if(s-p >=0)
	    {
	    	s=s-p;count++;
	    }
	    else
	    	s-=p;
	    if(p-d>m)
	    p-=d;
		else
		p=m;
	}
	cout<<count;
}