#!/bin/python3

import sys

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

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