#include <iostream>

using namespace std;

int main()
{
	int p,d,m,s;
	cin>>p>>d>>m>>s;

	int count=0;
	while(s-p>=0)
	{
		s-=p;
		count++;
		p=p-d>m?p-d:m;
	}	

	cout<<count<<endl;
	return 0;
}