public static int[] removeDuplicates(int[] input){
         
        int j = 0;
        int i = 1;
        //return if the array length is less than 2
        if(input.length < 2){
            return input;
        }
        while(i < input.length){
            if(input[i] == input[j]){
                i++;
            }else{
                input[++j] = input[i++];
            }   
        }
        int[] output = new int[j+1];
        for(int k=0; k<output.length; k++){
            output[k] = input[k];
        }
         
        return output;
    }