#include<bits/stdc++.h>
using namespace std;
int main()
{
	int p,d,m,s,i,sum=0,flag;
	cin>>p>>d>>m>>s;
	for(i=p;s>=sum;i=i-d)
	{
		if(i-d<m)
		{
		flag++;
		sum=sum+i;
	    i=m+d;
		}
		
	    else
		{
		flag++;
		sum=sum+i;
		}		
		
	}
	cout<<flag-1;
}