#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 count=0;
    for(int i=p;s>=0;p-=d){
       if(p<m)
           p=m;
       
       if(s>=p){
        count++;
           s-=p;
       }
       else
           break;
        
        
    }
    cout<<count;
    return 0;
}