func main()
	var n: int :: cui@inputInt()
	var max: int :: 60
	var x: []bool :: #[max + 1]bool
	for(1, n)
		var a: bit64 :: cui@inputInt() $ bit64
		for i(0, max)
			if(a.and((2 ^ i) $ bit64) <> 0b64)
				do x[i] :: true
			end if
		end for
	end for
	
	for i(0, max)
		if(!x[i])
			var ans: int :: 2 ^ i
			do cui@print("\{ans}\n")
			ret
		end if
	end for
end func