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


int main() {
    int p,d,m,s;
    int total=0;
    cin>>p>>d>>m>>s;
    //first game
    if(s-p<0)
    {
        cout<<"0"<<endl;
        return 0;
    }
    s-=p;
    total++;
    int cost=p-d;
    while(s>=0)
    {
        if(cost>m)
        {
            if(s-cost<0)
            {
                cout<<total<<endl;
                return 0;
            }
            s-=cost;
            total++;
            cost-=d;
        }
        else
        {
            if(s-m<0)
            {
                cout<<total<<endl;
                return 0;
            }
            s-=m;
            total++;
        }
    }
    
    cout<<total<<endl;
    return 0;
}