func main()
	var ss: [][]char :: cui@input().split(" ")
	var n: int :: ss[0].toInt(&)
	var m: int :: ss[1].toInt(&)
	var p: int :: ss[2].toInt(&)
	var q: int :: ss[3].toInt(&)
	
	var ans: int :: n / ((12 + q) * m) * 12
	do n :% ((12 + q) * m)
	if(n <> 0)
		for month(1, 12)
			do ans :+ 1
			do n :- m * ((p <= month & month < p + q) ?(2, 1))
			if(n <= 0)
				break month
			end if
		end for
	end if
	
	do cui@print("\{ans}\n")
end func