import java.util.* import java.io.* val pw = PrintWriter(System.out) val MOD = 1000000007L val INF = 2147483647 val LINF = 9223372036854775807L fun main(args: Array){ solve() pw.flush() } fun solve(){ val n = nextInt() val a = nextIntList() val b = IntArray(n) { 0 } val c = IntArray(n) { 0 } for (i in 0 until 2 * n step 2) { b[i / 2] = a[i] - a[i + 1] } for (i in 2 * n - 2 downTo 0 step 2) { c[i / 2] = a[i + 1] - a[i] } val s = IntArray(n + 1) { 0 } val t = IntArray(n + 1) { 0 } for (i in b.indices) { s[i + 1] = s[i] + b[i] } for (i in n - 1 downTo 0) { t[i] = t[i + 1] + c[i] } var ans = 0 for (i in 0..n) { ans = max(ans, s[i] + t[i]) } println(ans) } // Print fun println(v: String){ pw.println(v) } fun print(v: String){ pw.print(v) } // Read fun next() = readLine()!! fun nextInt() = next().toInt() fun nextLong() = next().toLong() fun nextDouble() = next().toDouble() fun nextList() = next().split(" ") fun nextIntList() = next().split(" ").map{ it.toInt() } fun nextLongList() = next().split(" ").map{ it.toLong() } fun nextDoubleList() = next().split(" ").map{ it.toDouble() } fun nextAryln(n: Int) = Array(n){ next() } fun nextIntAryln(n: Int) = IntArray(n){ nextInt() } fun nextLongAryln(n: Int) = LongArray(n){ nextLong() } fun nextDoubleAryln(n: Int) = DoubleArray(n) { nextDouble() } // Math fun abs(n: Int) : Int = Math.abs(n) fun abs(n: Long) : Long = Math.abs(n) fun abs(n: Double) : Double = Math.abs(n) fun max(a: Int = -INF, b: Int = -INF, c: Int = -INF, d: Int = -INF, e: Int = -INF): Int = listOf(a, b, c, d, e).max()!! fun max(a: Long = -LINF, b: Long = -LINF, c: Long = -LINF, d: Long = -LINF, e: Long = -LINF): Long = listOf(a, b, c, d, e).max()!!.toLong() fun min(a: Int = INF, b: Int = INF, c: Int = INF, d: Int = INF, e: Int = INF): Int = listOf(a, b, c, d, e).min()!! fun min(a: Long = LINF, b: Long = LINF, c: Long = LINF, d: Long = LINF, e: Long = LINF): Long = listOf(a, b, c, d, e).min()!!.toLong() fun prime(from: Long, to: Long = from) : List{ return (from..to).filter{ i -> val max = Math.sqrt(i.toDouble()).toLong() (2..max).all{ j -> i % j != 0L} } } fun gcd(a: Long, b: Long) : Long = if(a % b == 0L) b else gcd(b, (a % b)) fun lcm(a: Long, b: Long) : Long = a / gcd(a, b) * b fun modpow(a: Long, n: Long, p:Long = MOD) : Long { var res = 1L var ar = a var nr = n while(nr > 0){ if((nr and 1) == 1L) res = res * ar % p ar = ar * ar % p nr = nr shr 1 } return res } fun modinv(a: Long, p: Long = MOD) : Long = modpow(a, p - 2, p) fun ncr(n: Long, r: Long) : Long { var a = 1L var b = 1L for (i in 1..r) { a = a * (n + 1 - i) % MOD b = b * i % MOD } return modinv(b, MOD) * a % MOD }