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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int ans=0,x=0,count=0;
    while(ans<=s){
        if(x==0){
            ans=ans+p;
          
            count++;
            x=1;
        }else{
            p=p-d;
            if(p>=m){
                ans=ans+p;
                
                count++;
            }else{
                
                ans=ans+m;
                
                count++;
            }
        }
    }
    
     cout<<count-1<<endl;
    return 0;
}