{"raw_statement":[{"iden":"statement","content":"See the problem statement here: [http://codeforces.com/contest/921/problem/01](//codeforces.com/contest/921/problem/01)."}],"translated_statement":[{"iden":"statement","content":"请在此处查看题目描述：http://codeforces.com/contest/921/problem/01.\n\n"}],"sample_group":[],"show_order":[],"formal_statement":"**Definitions**  \nLet $ t \\in \\mathbb{Z} $ be the number of test cases.  \nLet $ T = \\{(n_k, A_k) \\mid k \\in \\{1, \\dots, t\\}\\} $ be the set of test cases, where for each $ k $:  \n- $ n_k \\in \\mathbb{Z} $ denotes the length of the sequence.  \n- $ A_k = (a_{k,1}, a_{k,2}, \\dots, a_{k,n_k}) $ is a sequence of integers.  \n\n**Constraints**  \n1. $ 1 \\le t \\le 1000 $  \n2. For each $ k \\in \\{1, \\dots, t\\} $:  \n   - $ 1 \\le n_k \\le 50 $  \n   - $ 1 \\le a_{k,i} \\le 100 $ for all $ i \\in \\{1, \\dots, n_k\\} $  \n\n**Objective**  \nFor each test case $ k \\in \\{1, \\dots, t\\} $, compute the alternating sum:  \n$$ S_k = \\sum_{i=1}^{n_k} (-1)^{i-1} a_{k,i} $$","simple_statement":null,"has_page_source":false}