public static int diffValues(int arr[], int p){
    if(p == arr.length)
        return 0;

    if(exist(arr,p+1,arr[p]))
        return diffValues(arr,p+1);
    else
        return diffValues(arr,p+1) + 1;
}

//checks if 'val' exists in the last p indexes of array 'arr'.
//(Implement that on your own)
public static boolean exist(int arr[], int p, int val);