#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    long long p,d,m,s;
    cin>>p>>d>>m>>s;
    
    long long price;
    long long count = 0;
    while(0<s)
    {
        price = p - count*d;
        if(price < m)
        {
            price = m;
        }
        
        s = s  - price;
        if(0 <= s)
        {
            count++;
        }
    }
    
    cout<<count;
    
    return 0;
}