#!/bin/python

import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    count=0
    while(s>=p):
        if(m<p):
            count=count+1
            s=s-p
            p=p-d
            if(p<m):
                p=m
            
        else:
            p=m
            s=s-p
            count=count+1
            
            
    return count 
            
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