#!/bin/python

import sys

               

if __name__ == "__main__":
    p, d, m, s = raw_input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    
    L=[p]    
       
    while sum(L)<=s:
        if m<=p-d:
            p=p-d
            L.append(p)
        else:
            L.append(m)
    
    ##print L
    
    i=0
    
    sum_=0
    
    for j in L:
        if sum_+j<=s:
            sum_=sum_+j
            i=i+1
   
    print i