#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 p, d, m, s;
    cin >> p >> d >> m >> s;
    int count = 0; 
    while ( true ) {
        if (s < p) break; else {
            s -= p;
            ++count;
            if (p > m) {
                
                if (p - d >= m) p -= d; else p =m;
            }
        }
    }
    cout << count;
    return 0;
}