#!/bin/python3

import sys

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

if __name__ == "__main__":
    p, d, m, s = input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    
    if m >= 1 and m <= p and p >= m and p <= 100 and d >= 1 and d <= 100 and s >= 1 and s <= 10000:
        answer = howManyGames(p, d, m, s);
    else:
        answer = False;
 
    print(answer);