FairRations.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class FairRations {

    // Complete the fairRations function below.
    static int fairRations(int[] B) {
       int counter = 0;
       if(firstOdd(B) == -1){
           return 0; 
       }
       int i = 0;
       while(i < B.length-1){
            if(B[i]%2 != 0){
                B[i]++;
                B[i+1]++;
                counter += 2;
            }     
            i++; 
       }
       if(B[B.length-1]%2 != 0){
           return -1;
       }

       return counter;

    }

    static int firstOdd(int[] B){
        for(int i=0;i<B.length;i++){
          if(B[i]%2 != 0){
             return i;
          }
        }
        return -1;
    }


    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int N = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        int[] B = new int[N];

        String[] BItems = scanner.nextLine().split(" ");
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int i = 0; i < N; i++) {
            int BItem = Integer.parseInt(BItems[i]);
            B[i] = BItem;
        }

        int result = fairRations(B);
        if(result != -1){
            bufferedWriter.write(String.valueOf(result));
            bufferedWriter.newLine();
            bufferedWriter.close();
        }else{
            bufferedWriter.write(String.valueOf("NO"));
            bufferedWriter.newLine();
            bufferedWriter.close();  
        }
        
        scanner.close();
    }
}