#include <bits/stdc++.h>
using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int curMoney= s;
    int nextGamePrice = p;
    int gameBought = 0;
    while(nextGamePrice <= curMoney){
        gameBought++;
        curMoney -= nextGamePrice;
        if(nextGamePrice - d >= m){
            nextGamePrice-= d;
        }else{
            nextGamePrice = m;
        }
    }
    return gameBought;
}

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;
}