Problem
Prince and Princess play a game "Timber Topple". Prince arranged several columns in a row, which must be knocked down with a bat in order. Prince knocked down the columns one after the other, starting from the very left, Princess - from the right. At some point, they knocked the last column together.
After that, Prince said that he had forgotten how many posts there were, but he remembers how many he shot down himself, and Princess said how many posts she shot.
Help Prince determine how many columns were in the beginning.
Input format
Two numbers are input - the number of columns that Prince and Princess shot down, respectively (each not more than 100).
Output format
Output the number of columns that were installed at the beginning of the game.
Example