Find the number - Problems

Find the integer value of n, if its previous and next numbers are known.

Input

Two integers - the previous and the next number for n, given in any order in one line, space separated. The numbers do not exceed 10⁹ by absolute value.

Output

Print the value of n.

Time limit 1 second

Memory limit 128 MiB

Input example #1

6 8

Output example #1

Input example #2

-16 -18

Output example #2

-17

Author Matviychuk Sergiy

Source "ABC programming"

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