Given this paragraph about Singapore, who was Singapore's first president?

Context: After being expelled from Malaysia, Singapore became independent as the Republic of Singapore on 9 August 1965, with Lee Kuan Yew and Yusof bin Ishak as the first prime minister and president respectively. In 1967, the country co-founded the Association of Southeast Asian Nations. Race riots broke out once more in 1969. Lee Kuan Yew's emphasis on rapid economic growth, support for business entrepreneurship, and limitations on internal democracy shaped Singapore's policies for the next half-century. Economic growth continued throughout the 1980s, with the unemployment rate falling to 3% and real GDP growth averaging at about 8% up until 1999. During the 1980s, Singapore began to shift towards high-tech industries, such as the wafer fabrication sector, in order to remain competitive as neighbouring countries began manufacturing with cheaper labour. Singapore Changi Airport was opened in 1981 and Singapore Airlines was formed. The Port of Singapore became one of the world's busiest ports and the service and tourism industries also grew immensely during this period.

Answer: Yusof bin Ishak