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


int main() {
    int m,p,d,s,cnt=0;
    cin>>p>>d>>m>>s;
    int sum=0;
    while(1){
        if(sum<=s){
            if(p>m){
            sum=sum+p;
                p=p-d;
                cnt++;
            }else{
       
                sum=sum+m;
                cnt=cnt+1;
            }
        }
        else
            break;
    }
    cout<<cnt-1;
    return 0;
}