let n = Int(readLine()!)!
let A = readLine()!.split(separator: " ").map{Int($0)!}

var dp0 = [Int](repeating: -1, count: n)
var dp1 = [Int](repeating: -1, count: n)

dp1[0] = -A[0]
if n > 1{
dp0[1] = -A[0]+A[1]
dp1[1] = dp1[0]
}

if n > 2{
for i in 2..<n{
    dp0[i] = max(dp0[i-1],dp1[i-1]+A[i])
    dp1[i] = max(dp1[i-1],dp0[i-1]-A[i])
}
}

if n == 1{
    print(dp1[0])
}else{
    print(max(dp0[n-1],dp1[n-1]))
}