func main()
	var n: int :: cui@inputInt()
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: cui@inputInt()
	end for
	
	var ans: int :: n
	for i(n - 1, 0, -1)
		if(a[i] = ans)
			do ans :- 1
		end if
	end for
	do cui@print("\{ans}\n")
end func