import Foundation

let input = readLine()!.components(separatedBy: " ").map({ Int($0)! })
var p = input[0]
let d = input[1]
let m = input[2]
let s = input[3]

var cost = 0
var count = 0

while cost <= s
{
    cost += p
    
    if cost <= s
    {
        if p >= m + d
        {
            p -= d
        }
        else if p > m
        {
            p = m
        }
        
        count += 1
    }
}

print(count)