#include <bits/stdc++.h>
using namespace std;
 
#define fr(i,a,b) for(int (i)=(int) a;(i)<=(int)(b);++(i))
#define li list<int>
#define ll long long
#define mp make_pair
#define mod 1000000007
#define pb push_back
#define pi pair<int ,int >
#define pr printf
#define vi vector<ll>
#define vpi vector< pi > 

int main()
{
	int n=10,i,j;
	int p,d,m,s,res=0,cost=0,b;
	cin>>p>>d>>m>>s;
	p+=d;
	while(1)
	{
		b=max(m,p-d);
		if(cost+b>s) break;
		cost+=b;
		res++;
		p-=d;
	}
	cout<<res;
	return 0;
}