CF322A.Ciel and Dancing

Fox Ciel and her friends are in a dancing room. There are n boys and m girls here, and they never danced before. There will be some songs, during each song, there must be exactly one boy and one girl are dancing. Besides, there is a special rule:

• either the boy in the dancing pair must dance for the first time (so, he didn't dance with anyone before);
• or the girl in the dancing pair must dance for the first time.

Help Fox Ciel to make a schedule that they can dance as many songs as possible.

小狐狸Ciel和她的朋友们在一个舞蹈室里。这里有 $n$ 个男孩和 $m$ 个女孩，且他们此前从未跳过舞。接下来将播放若干首歌曲；每首歌播放时，必须恰好有一名男孩和一名女孩在跳舞。此外，还有一条特殊规则：

• 跳舞的男孩必须是第一次跳舞（即他此前从未与任何人跳过舞）；
• 或者跳舞的女孩必须是第一次跳舞。

请帮助小狐狸Ciel制定一个安排方案，使得他们能够跳尽可能多的歌曲。

The first line contains two integers n and m (1 ≤ n, m ≤ 100) — the number of boys and girls in the dancing room.

第一行包含两个整数 $n$ 和 $m$（$1 \leq n, m \leq 100$）—— 分别表示舞厅中男孩和女孩的人数。

In the first line print k — the number of songs during which they can dance. Then in the following k lines, print the indexes of boys and girls dancing during songs chronologically. You can assume that the boys are indexed from 1 to n, and the girls are indexed from 1 to m.

第一行输出 k —— 他们可以跳舞的歌曲数量。随后的 k 行中，按时间顺序输出每首歌期间跳舞的男孩和女孩的编号。你可以假设男孩的编号为 1 到 n，女孩的编号为 1 到 m。

In test case 1, there are 2 boys and 1 girl. We can have 2 dances: the 1st boy and 1st girl (during the first song), the 2nd boy and 1st girl (during the second song).

And in test case 2, we have 2 boys with 2 girls, the answer is 3.

在测试用例 1 中，有 2 名男生和 1 名女生。我们可以安排 2 支舞：第 1 名男生与第 1 名女生（在第一首歌曲期间），第 2 名男生与第 1 名女生（在第二首歌曲期间）。

而在测试用例 2 中，我们有 2 名男生和 2 名女生，答案为 3。