Legend has it that Indian King Shehan intends to reward Sass Bandal, the inventor of chess. The wise minister knelt before the king and dared to say, "Your Majesty, please give me a grain of wheat in the first box, two grains in the second box and four grains in the third box. At this rate, each carriage is twice as big as the previous one. " The king said, "Your requirements are not high, and you will get what you want." With that, he ordered a bag of wheat to be taken to the throne, and the work of calculating wheat grains began ... Before the twentieth cell, the bag was empty, and bags of wheat were transported to the king. However, the number of wheat grains increased rapidly one after another, and it soon became clear that the king could do it even if all the grains in India were taken out.

How much wheat should the king give the inventor?