CF813F.Bipartite Checking

You are given an undirected graph consisting of n vertices. Initially there are no edges in the graph. Also you are given q queries, each query either adds one undirected edge to the graph or removes it. After each query you have to check if the resulting graph is bipartite (that is, you can paint all vertices of the graph into two colors so that there is no edge connecting two vertices of the same color).

给你一个包含 $n$ 个顶点的无向图。初始时图中没有边。此外，你还会收到 $q$ 个查询，每个查询要么向图中添加一条无向边，要么删除一条无向边。每次查询后，你都需要判断当前图是否为二分图（即能否将图中所有顶点染成两种颜色，使得任意一条边所连接的两个顶点颜色不同）。

The first line contains two integers n and q (2 ≤ n, q ≤ 100000).

Then q lines follow. _i_th line contains two numbers x__i and y__i (1 ≤ x__i < y__i ≤ n). These numbers describe _i_th query: if there is an edge between vertices x__i and y__i, then remove it, otherwise add it.

第一行包含两个整数 $n$ 和 $q$（$2 \le n, q \le 100000$）。

接下来是 $q$ 行。第 $i$ 行包含两个数 $x_i$ 和 $y_i$（$1 \le x_i < y_i \le n$）。这些数描述了第 $i$ 个查询：如果顶点 $x_i$ 和 $y_i$ 之间存在一条边，则将其删除；否则添加该边。

Print q lines. _i_th line must contain YES if the graph is bipartite after _i_th query, and NO otherwise.

输出 q 行。第 i 行必须包含 YES（如果在第 i 次查询后该图是二分图），否则包含 NO。