#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 sum=0, count=0, cost=p;
    while (s>=(sum+cost)){
        if ((cost-d)>m){
            sum+=cost;
            cost-=d;
            
        } else {
            sum+=m;
            
        }
        ++count;
       
    }
    cout<<count;
    return 0;
}