#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int x = (p - m) / d;
    int cost = p;
    int t_a = 0, a = 0, sum_a = 0;    
    while (1) {    
        sum_a += cost;
        a++;
        if (cost - m >= d) { cost -= d; } else { break; }
        if (sum_a == s) { return a; }
        else if (sum_a > s) {return a-1; }        
    }    
    return a + (s - sum_a) / m;
    
}

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;
}