#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,ans=0;
    cin>>p>>d>>m>>s;
    int c=p;
    while(c>=m)
    {
        if(s-c<0)
            break;
        else
        {
            s-=c;
            ans++;
            if(c-d>=m)
                c-=d;
            else
               c=m; 
        }
    }
    cout<<ans;
    return 0;
}