#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    //p-d m
    int total = p;
    int numgames = 0;
    int prevprice = p;
    int i = 1;
    int prevtotal = 0;
    while(total<=s)
    {
        int amount;
        if(p - i*d < m) amount = m;
        else amount = p - i*d;
        prevtotal = total;
        total+=amount;
        //prevprice=amount;
        numgames++;
        i++;
    }
    return numgames;
}

int main() {
    int p;
    int d;
    int m;
    int s;
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}