The smallest unimaginable

For a given set consisting of positive integers, determine the smallest positive number, unimaginable as the sum of the elements of any subset of the set.

Input

The input file contains all the numbers that make up a given set. Each of them does not exceed 10^15, the total amount does not exceed 10000, and their sum is guaranteed to not exceed 2^64-1.

Output

In the output file to bring a single number - the answer of the problem.

Examples