Addressing students on the occasion of the 125th anniversary of Swami Vivekananda's famous address at World Parliament of Religions in Chicago, Prime Minister Narendra Modi on Monday again stressed on the need for all Indian citizens to join in the campaign for a "Clean India", saying citizens should think fifty times and ask themselves whether they have the right to chant 'Vande Mataram' when they can't keep the country clean or abuse the land on which they live.