#!/bin/ruby

def howManyGames(p, d, m, s)
    cost = 0
    ans = 0
    while cost <= s do
        cost += p - (ans * d) < m ? m : p - (ans * d) 
        ans += 1
    end
    
    ans - 1
end

p, d, m, s = gets.strip.split(' ')
p = p.to_i
d = d.to_i
m = m.to_i
s = s.to_i
answer = howManyGames(p, d, m, s)
puts answer