func main()
	var n: int :: cui@input().toInt(&)
	var ss: [][]char :: cui@input().split(" ")
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: ss[i].toInt(&)
	end for
	
	var ans: int :: 0
	var prev: int :: -1
	var prevId: int :: -2
	for i(0, n - 1)
		if(prevId = i - 2 | a[i] = prev)
			do prevId :: i
			do prev :: a[i]
			do ans :+ 1
		end if
	end for
	do cui@print("\{ans}\n")
end func