source_code: 
  import java.util.Scanner;
  
  public class Main {
  
      /**
       * @param args
       */
      public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int n = sc.nextInt();
          int[] nums = new int[n];
          int kisu = 0;
          int gusu = 0;
          for(int i = 0 ; i < n ; i++){
              nums[i] = sc.nextInt();
              if(nums[i] % 2 == 0)gusu++;
              if(nums[i] % 2 == 1)kisu++;
          }
          int ans = -1;
          if(gusu == 1){
              for(int i = 0 ; i < n ; i++){
                  if(nums[i]%2 == 0){
                      ans = i+1;
                      break;
                  }
              }
          }
          else{
              for(int i = 0 ; i < n ; i++){
                  if(nums[i]%2 == 1){
                      ans = i+1;
                      break;
                  }
              }
              
          }
          System.out.println(ans);
      }
  
  }
  