#include <bits/stdc++.h>
using namespace std;

#define ll int64_t
#define v vector


int main()
{
    ll p,d,m,s;
    cin>>p>>d>>m>>s;

    ll cost = 0;
    ll count = 0;
    while(cost <= s)
    {
        if(p > m)
        {
            cost += p;
            p -= d;
            count++;
        }

        else
        {
            cost += m;
            count++;
        }

    }

    cout<<count-1;
    return 0;
}