#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 */   
    long int p,d,m,s;
cin>>p>>d>>m>>s;
    int sum=0,count=0,x=0;
    while(sum<s)
    {
        if(p>m){
        sum+=p;
        // cout<<p<<" ";
        p=p-d;
            if(p<m)
                p=0;
            if(sum<=s)count++;
            else break;
        }
        else
        {
            sum+=m;
            if(sum<=s)count++;
            else break;
        }
        
    }
    cout<<count;
    return 0;
}