The smallest number#5726
Given a sorted list of natural numbers A_1 < \ldots < A_N.
Your task is to find the smallest natural number that cannot be expressed as the sum of any subset of numbers from this list. You may use each number from the list at most once, and the sum can be composed of just one number.
The first line contains a single integer (1 \leq N \leq 10^6)—the number of elements in the list. The second line contains the elements of the list, separated by spaces. All elements are distinct natural numbers, sorted in increasing order, and each does not exceed 10^6.
The input data is guaranteed to be correct.
Output a single integer—the smallest natural number that cannot be formed as described.
Example 1