On 28 April 1975, Kurt Waldheim, the UN Secretary-General, launched a new mission of good offices. Starting in Vienna, over the course of the following ten months Clerides and Denktaş discussed a range of humanitarian issues relating to the events of the previous year. However, attempts to make progress on the substantive issues – such as territory and the nature of the central government – failed to produce any results. After five rounds the talks fell apart in February 1976. In January 1977, the UN managed to organise a meeting in Nicosia between Makarios and Denktaş. This led to a major breakthrough. On 12 February, the two leaders signed a four-point agreement confirming that a future Cyprus settlement would be based on a federation. The size of the states would be determined by economic viability and land ownership. The central government would be given powers to ensure the unity of the state. Various other issues, such as freedom of settlement and freedom of movement, would be settled through discussion. Just months later, in August 1977, Makarios died. He was replaced by Spyros Kyprianou, the foreign minister.