#!/bin/python3

import sys

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