#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, ans, sum = 0;
    cin >> p >> d >> m >> s;
    for (ans = 1 ; ; ++ans) {
        sum += max(p - (ans - 1) * d, m);
        if (sum > s) {
            --ans;
            break;
        }
    }
    cout << ans << endl;
    
    return 0;
}