object Solution {

    def howManyGames(price: Int, discount: Int, minPrice: Int, startAmount: Int): Int =  {
        // Return the number of games you can buy
        
        @annotation.tailrec
        def loop(currentPrice: Int, currentAmount: Int, bought: Int): Int = {
           if(currentAmount < currentPrice) bought
           else {
            val newBought = bought + 1
            val newCurrentPrice = if (currentPrice - discount >= minPrice) currentPrice - discount else minPrice
            loop(newCurrentPrice, currentAmount - currentPrice, newBought)   
           }
        }
        loop(price, startAmount, 0)
    }

    def main(args: Array[String]) {
        val sc = new java.util.Scanner (System.in);
        var p = sc.nextInt();
        var d = sc.nextInt();
        var m = sc.nextInt();
        var s = sc.nextInt();
        val answer = howManyGames(p, d, m, s);
        println(answer)
    }
}