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