This problem is perhaps one of the most well known mathematical puzzles of the last hundred years. According to Wikipedia, a short story writer Ben Williams modified an older problem and included it in a story in the October 9, 1926 issue of The Saturday Evening Post. The magazine was swamped by interested readers wanting a solution. Much later Martin Gardner (1914-2010), the American popular mathematics writer, featured the problem in his April 1958 Mathematical Games column in the magazine Scientific American. Gardner once told his son that it was his favourite puzzle.