#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, c=0;
    cin>>p>>d>>m>>s;
    
    while(s>=0 && p>=m) {
        s=s-p;
        if(s>=0) {
            c++;
            if(p-d>=m)
                p = p-d;
            else
                p=m;
        }
    }
    
    
    
    cout<<c<<endl;
    return 0;
}