#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define DHOKHA ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
int main()
{
   DHOKHA;
   ll p,d,m,s;
   cin>>p>>d>>m>>s;
   ll c=0;
   while(1)
   {
     	
   	
   	  if(p<=m)
   	  {
   	  	s-=m;
   	  }
   	  else
   	  {
   	  	 s-=(p);
   	  	 p-=d;
   	  }
   	  if(s<0)
   	  {
   	  	break;
   	  }
   	  else
   	  {
   	  	c++;
   	  }
   	  
   	  
   	 
		 
   }
   cout<<c;
   
}