#!/bin/python

import sys

def howManyGames(p, d, m, s):
    array = [p]
    rest = p-d
    while (rest >= m):
        array.append(rest)
        rest -= d
    sum_cost = 0
    i = 0
    n = len(array)
    while (i < n and s >= sum_cost):
        sum_cost += array[i]
        i += 1
    while (s >= sum_cost):
        sum_cost += m
        i += 1

    return i-1


if __name__ == "__main__":
    p, d, m, s = raw_input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    answer = howManyGames(p, d, m, s)
    print answer