SCUT_Pein

Problem Description 有一种纸牌游戏，很有意思，给你N张纸牌，一字排开，纸牌有正反两面，开始的纸牌可能是一种乱的状态（有些朝正，有些朝反），现在你需要整理这些纸牌。但是麻烦的是，每当你翻一张纸牌（由正翻到反，或者有反翻到正）时，他左右两张纸牌（最左边和最右边的纸牌，只会影响附近一张）也必须跟着翻动，现在给你一个乱的状态，问你能否把他们整理好，使得每张纸牌都正面朝上，如果可以，最

Description In Korea, the naughtiness of the cheonggaeguri, a small frog, is legendary. This is a well-deserved reputation, because the frogs jump through your rice paddy at night, flattening rice

As usual, Sereja has array a, its elements are integers: a[1], a[2], ..., a[n]. Let's introduce notation: A swap operation is the following sequence of actions: choose two indexes i, j (i