import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws NumberFormatException, IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int cases = Integer.parseInt(br.readLine());

        while(cases-- > 0){
            int wordNumber = Integer.parseInt(br.readLine());
            StringBuffer result = new StringBuffer();
            while(wordNumber-- > 0){
                if(wordNumber == 0){
                    result.append(br.readLine());
                } else {
                    result.append(br.readLine() + ",");
                }
            }
            for(int i=1;i<result.length()-1;i++){
                if(result.charAt(i) == '-'){
                    if(result.charAt(i+1) == ','){
                        result.delete(i, i+1);

                    }
                    if(result.charAt(i-1) == ' ' || result.charAt(i+1) == ' '){
                        result.delete(i, i+1);
                        i--;
                    } else if(isCharter(result.charAt(i-1)) && isCharter(result.charAt(i+1))){
                        result.delete(i, i+1);
                        i--;
                    } else {
                        result.delete(i, i+1);
                        result.insert(i, ' ');
                    }
                } else if(result.charAt(i) == ','){
                    if(isCharter(result.charAt(i-1)) && isCharter(result.charAt(i+1))){
                        result.delete(i, i+1);
                        result.insert(i, ' ');
                    }
                }
            }
            StringTokenizer st = new StringTokenizer(result.toString());
            double avr = 0;
            int n = 0;
            while(st.hasMoreTokens()){
                avr += st.nextToken().length();
                n++;
            }
            avr = avr/n;
            avr = decimalScale(avr, 3);
            System.out.printf("%.3f\n", avr);
        }
    }
    public static boolean isCharter(char ch){
        if(ch >= 'a' && ch <= 'z'){
            return true;
        } else{
            return false;
        }
    }
    public static double decimalScale(double decimal , int loc) {
       BigDecimal bd = new BigDecimal(decimal);
       BigDecimal result = null;
       result = bd.setScale(loc, BigDecimal.ROUND_HALF_UP);   //반올림

       return result.doubleValue();
    }
}