#!/bin/python3

import sys

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

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)