func main()
	var s: []char :: cui@input()
	var f: bool :: false
	for i(0, ^s - 1)
		if (i = 0 & s[i] <> '1')
			do f :: true
		end if
		if (i <> 0 & s[i] <> '3')
			do f :: true
		end if 
	end for
	if (f | ^s = 1)
		do cui@print("-1")
	else
		do cui@print((^s-1).toStr())
	end if
end func