UVA - 406 - Prime Cuts

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        StringBuffer sb = new StringBuffer("");
        String m = "";
        boolean notPrime[]=sievePrime(1000);
        ArrayList<Integer> arr=new ArrayList<Integer>();
        for(int i=1;i<1001;i++){
            if(!notPrime[i]){
                arr.add(i);
            }
        }
        while ((m=br.readLine())!=null) {
            String[] str=m.split(" ");
            int n = Integer.parseInt(str[0]);
            int c = Integer.parseInt(str[1]);
            int index=-1 ,temp=n;
            while(index==-1){
                index =arr.indexOf(temp);
                temp--;
            }
            List<Integer> subArr=arr.subList(0, index+1);
            if(2*c<subArr.size()){
                if(subArr.size()%2==0){
                   subArr=arr.subList((subArr.size()-2*c)/2, (subArr.size()+2*c)/2);
                }
                else{
                   subArr=arr.subList((subArr.size()-2*c+2)/2, (subArr.size()+2*c)/2);
                }
            }
            sb.append(n).append(" ").append(c).append(":");
            for(int i=0;i<subArr.size();i++){
                sb.append(" ").append(subArr.get(i));
            }
            sb.append("\n\n");
        }
        System.out.print(sb);
    }

static boolean [] sievePrime(int x){
        boolean[] notPrime = new boolean[x + 1];
        notPrime[0]=true;
        notPrime[1]=false;
        for (int i = 2; i*i < x+1; i++) {
            if (!notPrime[i]) {
                for (int j = i; i*j < x+1; j++) {
                    notPrime[i*j] = true;
                }
            }
        }
        return notPrime;
    }
 
}