#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
   int p,d,m,s;
    cin>>p>>d>>m>>s;
    if(p>s)
    {cout<<"0";
     return 0;
        
    }
   
  int k=0;
   int l=0;
    
    
   do
    {k+=p;
     
     if((p-d)>m)
         p=p-d;
     else
         p=m;
     
     
      l++;  
        
        
        
        
    }while(k<=s);
    cout<<l-1;
    return 0;
}