Four merry tramps bought, borrowed, found, or in some other manner obtained possession of a box of biscuits, which they agreed to divide equally amongst themselves at breakfast next morning. 

In the night, while the others were fast asleep under the greenwood tree, one man approached the box, devoured exactly a quarter of the number of biscuits, except the odd one left over, which he threw as a bribe to their dog. 
Later in the night a second man awoke and hit on the same idea, taking a quarter of what remained and giving the odd biscuit to the dog. 
The third and fourth men did precisely the same in turn, taking a quarter of what they found and giving the odd biscuit to the dog. 
In the morning they divided what remained equally amongst them, and again gave the odd biscuit to the animal. 
Every man noticed the reduction in the contents of the box, but, believing himself to be alone responsible, made no comments. 

What is the smallest possible number of biscuits that there could have been in the box when they first acquired it?