import java.util.*;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    
    int n = sc.nextInt();
    int l = sc.nextInt();
    
    int x = Math.abs(l);
    int k = 1;
    
    for(int i=2; i<=n; i++){
      if(x>Math.abs(l+i-1)){
        x = Math.abs(l+i-1);
        k = i;
      }
    }
    
    int ans = 0;
    
    for(int i=1; i<=n; i++){
      if(i!=k){
        ans += (l+i-1);
      }
    }
    
    System.out.println(ans);
  }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz