#include<iostream>
using namespace std;
int main()
{
	long int p,d,m,s,a=0,i,j,r,temp;
	cin>>p>>d>>m>>s;
	r=p;
	temp=p;
	a++;
	for(i=temp-d;i>=m;i-=d)
	{
		if(r<=s)
		{
		a++;
		r=r+i;
		temp=i;
	   }
	   else
	   break;
	}
	while(r<=s)
	{
		if(i<=m)
		{
			a++;
			r=r+m;
		}
	}
	cout<<a-1;
	return 0;
}