package main

import (
	"fmt"
	"strings"
)

func maxLength (arr []string) int {
	trace := ""
	res := 0
	n := len(arr)
	var backtrace func(idx int)
	backtrace = func(idx int) {
		res = max(res, len(trace))
		for i := idx ; i < n ; i ++ {
			if ! strings.ContainsAny(trace, arr[i]) && hasReapted(arr[i]) {
				trace += arr[i]
				backtrace(i + 1)
				trace = trace[:len(trace) -len(arr[i])]
			}
		}
	}
	backtrace(0)
	return res
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func hasReapted(s string) bool {
	iset := make([]int, 30, 30)
	for _, v := range s {
		if iset[v - 'a'] > 0 {
			return false
		}
	}
	return true
}

func main() {
	fmt.Println(strings.ContainsAny("un","ue"))
}