class Solution {
        public:

          long int  dp[1033][1004];

         int rec(vector<int>& A,int start,int end,int diff ){

        if(start>=A.size()){
             return 0;
          }
if(dp[start][end]!=0){
  return dp[start][end];
  }
      int o1=0,o2;

      o2= rec(A,start+1,end,diff);




if(A[start]-A[end]==diff){

o1 =  1+rec(A,start+1,start,diff);
       }

    return dp[start][end]=max(o1,o2);

        }


   int longestArithSeqLength(vector<int>& A) {
   int maxe=0;
memset(dp,0,sizeof(dp));
for(auto i=0;i<A.size();i++){

    for(auto j=i+1;j<A.size();j++){
        
      int  diff=A[j]-A[i];
        if(dp[j][i]==0){
     
            dp[j][i]=2+rec(A,j+1,j,diff);
        }
    
      if(maxe<=dp[j][i]){

      maxe=dp[j][i];
        }
    
    
           }
   
                 }
    return maxe;

    
    
}
   };