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