#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
    int sum = p;
    int count = 0;
    while (s >= sum)
    {
        count ++;
        
        if ((p - d) > m) 
            p = p - d;
        else 
            p = m;
        
        sum = sum + p;
    }
    
    return count;
}

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;
}