#include <bits/stdc++.h>

using namespace std;


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