The answer is 48.
The 2 that are commonly disputed are Russia and Turkey as they both are counted among Europe and Asia. If you count Cyprus, the Philippines and Hong Kong, there are 51.
The following are the 46 definite countries of Asia:
And then there are the debatable ones. 47. Hong Kong 48. Turkey 49. Russia 50. Cyprus 51. Philippines
Australia, New Zealand, Papua New Guinea, Palau, Nauru, Tuvalu, Kiribati, Vanuatu, Samoa, Fiji, Tonga, Micronesia, the Marshall Islands and the Solomon Islands are all located in Oceania.