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

typedef long long ll;

int main() {
    int p, d, m, s;
    cin >> p >> d >> m >> s;
    int mas[p/d+2];
    mas[0] = p;
    for(int i = 1; i < p/d + 2; i++){
        if(mas[i-1] == m)
            mas[i] = m;
        else{
            mas[i] = mas[i-1]-d;
            if(mas[i] < m)
                mas[i] = m;
        }
    }
    int i = 0, res = 0;
    if(s < mas[0]){
        cout << 0 ;
        return 0;
    }
    while(s >= 0){
        s -= mas[i];
       // cout << s << ' ' ;
        if(s >= 0)
            res++;
        if(i < p/d+1)
            i++;
    }
    cout << res;

    return 0;
}