Mango Juice

In a Juice centre there are some mangoes kept in a basket. The basket contains both small size mangoes and large size mangoes. If a juice seller wants to prepare a glass of juice he has to either use one large size mango or two small size mangoes. If a basket contains $M$ large mangoes and $N$ small size mangoes, how many glasses of mango juice can be prepared? ###Input: - The first line of