func main()
	var n: int :: cui@inputInt()
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: cui@inputInt()
	end for
	
	for i(0, n - 2)
		if(a[i] = a[i + 1])
			do cui@print("Yes\n")
			ret
		end if
	end for
	
	for i(0, n - 3)
		if(a[i] = a[i + 2])
			do cui@print("Yes\n")
			ret
		end if
	end for
	
	do cui@print("No\n")
end func