1027.longest arithmetic subsequence

class Solution {
    public int longestArithSeqLength(int[] arr) {
          int max=0;
    for(int i=0;i<arr.length-1;i++){
        for(int j=i+1;j<arr.length;j++){
            int diff=arr[j]-arr[i];
            int val=arr[j];
            int c=2;
            for(int k=j+1;k<arr.length;k++){
                if(arr[k]-val==diff){
                    val=arr[k];
                    c++;
                }
            }
            max=Math.max(c,max); 
        }
    }
    return max==0?1:max;
    }
}