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

using namespace std;

int howManyGames(int p, int d, int m, int s) 
{
    int curPrice = p;
    int res = 0;
    while(s >= 0)
    {
        if (s >= curPrice)
        {
            s -= curPrice;
            ++res;
        }
        else
        {
            break;
        }
        if (curPrice > m)
        {
            curPrice -= d;
        }
        
        if (curPrice < m)
            curPrice = m;
    }
    return res;
}

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;
}