Have a quite odd way Chocolate Distribution System: Here lets assume 64 (Classes) are number of chocolates being distributed, and it is told that we have 37 Teachers, Each teachers will be given 1 chocolate since mentioned, at least one class, Now there are 64-37= 27 chocolate to be remaining. To Minimize the number of 3 chocolates (Classes) we will distribute one each to everyone, again that way each would have 2 chocolates, But since there are only 27 chocolates it got exhausted in between due to which we don't have to give 3rd chocolate to anyone. Therefore least 0 can be given.
Now, to maximize i will try to give more chocolates since we have already given 1 , it would be three chocolates since we have 27 chocolates left we will give 26/2 = 13 teachers . Therefore maximum would be 13.