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.

The first line contains two integers $ n $ and $ m $ ( $ 1

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 $ .

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.