### Practice websites

We recommend the following websites for you to get practice and get familiar with the programming contest.

- Hackerrank
- Kattis
- AIZU online programming challenge
- USACO: USA Computing Olympiad (Training Resources)

### A sample problem

Problem: Given an array of integers, find the sum of its elements. Input Format The first line contains an integer, n, denoting the size of the array. The second line contains space-separated integers representing the array's elements. Constraints: 0 < n and the elements < 1000 Output Format Print the sum of the array's elements as a single integer. Sample Input 6 1 2 3 4 10 11 Sample Output 31