and display both the age and name of the child.It should work out the standard deviation of the age and display this to the use [closed]

import java.util.Scanner;
public class DataAnalysis {

    public static void main(String[] args) {
        
    Scanner in = new Scanner(System.in);
                /**System.out.println(!(4<1)|0>4);
                System.out.println(4<2|10>4);
                int a=12;
                System.out.println(a&13);*/
     System.out.println("How many entries?");
      int g = in.nextInt();//总共进行多少循环看着
      String[] gender = new String[g]; //循环次数 System.out.println("Please enter the name of Person 1:"+name);
      int[] age = new int[g];//dsadsadsfa
      String[] name = new String[g];
      
       int sd=0;   
       int c=0;//njlk
       int rt=0;
       do  { 
       sd+=c;   
      System.out.println("Please enter the name of Person :"+(c+1)); 
                     name[c] = in.next();
      System.out.println("Please enter the age of Person : "+(c+1));
                    age[c] =  in.nextInt();
     System.out.println("Please enter the gender of Person :"+(c+1));//input相关程序由4段
                     gender [c]= in.next(); 
     for( ; !gender [c].equals("M")&&!gender [c].equals("F"); gender [c]= in.next()) {
         System.out.println(" please enter M or F only:");//性别格式记下来，java词典保留下来，分号必须3个
     }

     
     
             if (gender [c].equals("M")) {
                rt++;
             }
          c++;               
          }while(c<=g-1);
          double mn= sd/g ;
          System.out.println("The gender ratio is" +((double)rt/g)+ "male and" +((double)(1-rt)/g)+ "female.");  
          System.out.println("The mean age is"+mn)      ;     

My questions: dont know how to compare age input among different put??????????????? than 18) and display both the age and name of the child.? how should I coduct the comparison among different ages??