A rectangular cake is transported via a truck to a restaurant. On the way to the destination, the truck hits a pothole, which shatters the cake in perfectly rectangular pieces of width and length , for .
At the destination, the damage is assessed, and the customer decides to order a replacement cake of the same dimensions. Unfortunately, the original order form was incompletely filled and only the width of the cake is known. The restaurant asks for your help to find out the length of the cake. Fortunately, all pieces of the shattered cake have been kept.
输入格式
The input consists of the following integers:
on the first line, the width of the cake;
on the second line, the number of shattered pieces;
on each of the next lines, the width and length of each piece.
