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