#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 n, d, m, s;
    cin >> n >> d >> m >> s;
    int ans = 0, i= 0;
    while(s >= 0){
        if(n - i*d < m)
            break;
        s = s - (n - d*i);
        i++;
        if(s >= 0)
            ans++;
    }
    if(s > 0)
    ans = ans + s/m; 
    cout << ans;
    return 0;
}