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


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