The Hindustani language (Hindi-Urdu) is the lingua franca of Pakistan and Northern India. Many Indian states have adopted the Three-language formula in which students in Hindi-speaking states are taught: "(a) Hindi (with Sanskrit as part of the composite course); (b) Urdu or any other modern Indian language and (c) English or any other modern European language." The order in non-Hindi speaking states is: "(a) the regional language; (b) Hindi; (c) Urdu or any other modern Indian language excluding (a) and (b); and (d) English or any other modern European language." Hindi has also emerged as a lingua franca for the locals of Arunachal Pradesh, a linguistically diverse state in Northeast India. It is estimated that 90 percent of the state's population knows Hindi.