#include <bits/stdc++.h>

using namespace std;

int main()
{
    int p,d,m,s;
    cin >> p >> d >> m >> s;
    int sum=0,count=0;
    while(sum<=s)
    {
        if(p>=m){
            sum+=p;
            p-=d;
        }
        else {
            sum+=m;
        }
        count++;
    }
    if(sum>s)
    cout<<count-1<<"\n";
    else cout <<count<<"\n";
    return 0;
}