{"raw_statement":[{"iden":"problem statement","content":"Given is an integer sequence $A_1, ..., A_N$ of length $N$.\nWe will choose exactly $\\left\\lfloor \\frac{N}{2} \\right\\rfloor$ elements from this sequence so that no two adjacent elements are chosen.\nFind the maximum possible sum of the chosen elements.\nHere $\\lfloor x \\rfloor$ denotes the greatest integer not greater than $x$."},{"iden":"constraints","content":"*   $2 \\leq N \\leq 2\\times 10^5$\n*   $|A_i|\\leq 10^9$\n*   All values in input are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$A_1$ $...$ $A_N$"},{"iden":"sample input 1","content":"6\n1 2 3 4 5 6"},{"iden":"sample output 1","content":"12\n\nChoosing $2$, $4$, and $6$ makes the sum $12$, which is the maximum possible value."},{"iden":"sample input 2","content":"5\n-1000 -100 -10 0 10"},{"iden":"sample output 2","content":"0\n\nChoosing $-10$ and $10$ makes the sum $0$, which is the maximum possible value."},{"iden":"sample input 3","content":"10\n1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000"},{"iden":"sample output 3","content":"5000000000\n\nWatch out for overflow."},{"iden":"sample input 4","content":"27\n18 -28 18 28 -45 90 -45 23 -53 60 28 -74 -71 35 -26 -62 49 -77 57 24 -70 -93 69 -99 59 57 -49"},{"iden":"sample output 4","content":"295"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}