public function findWord(){
        $arr = ["U>N", "G>A", "R>Y", "H>U", "N>G", "A>R"];
        $new = [];
        $inverted = [];
        $result = "";

        foreach ($arr as $rule) {
            $new[$rule[0]] = $rule[2];
            $inverted[$rule[2]] = $rule[0];
        }

        $first = null;
        foreach ($inverted as $key => $value) {
            if(empty($inverted[$value])){
                $first = $value;
                break;
            }
        }

        $letter = $first;

        while(!empty($new[$letter])){
            $result .= $letter;
            $letter = $new[$letter];
        }

        $result .= $letter;

        return $result;
    }