int solve(int i, int j, int[][]dp, int n){
  if(i<0 || j>=n)return 0;
  if(dp[i][j]!=-1)return dp[i][j];
  return dp[i][j]=arr[i]*arr[j]+Math.max(0, solve(i-1,j+1, dp,n))
}




for(int i=0;i<n;i++)
for(int j=i+1;j<n;j++){
  ans=Math.max(ans, solve(i,j,dp,n));
}
System.out.println(ans);