In Tokyo, Denis met a Japanese gardener. The gardener told Denis that
on some mornings one of the branches of his sakura straightened out, but in the
evening it was always bent again. The branch straightens no more often than once
a day, but the time when it will straighten or bend back is almost impossible
to predict. The gardener has installed an automated observation system, which
records the state of the branch every second. The statistics are collected and
published at the gardener's website in the form of a picture: a white pixel
denotes a bent branch and a black pixel denotes a straight branch. The
observations during one day are shown in a vertical column. The picture obtained
is rather strange: it's a set of vertical segments, with no more than one
segment in each column. Denis said that it was unpractical to draw this picture
pixelwise. It will be more efficient to draw it by means of rectangles, for
example, in JavaScript. Naturally, the gardener asked Denis to write a program
that would draw the picture showing the statistics. Denis will cope with the
JavaScript program himself, you only have to find the minimal set of rectangles
whose union coincides with the initial picture.
Input
The first line contains the vertical and horizontal dimensions of the picture: N
and M (1 ≤ N, M ≤ 50). The following lines contain the
picture itself: in each of N lines there are M symbols.
A black pixel is denoted by 1 and a white pixel is denoted by 0.
Output
In the first line output the number of the rectangles.
Then output the coordinates of their opposite corners.
Assume that the OX axis is directed downward and the OY axis
is directed to the right. If there are several solutions with the minimal
number of rectangles, then output any of the solutions.
Samples
input  output 

3 3
010
111
010
 2
1 2 3 2
2 1 2 3

4 5
00000
11100
11010
10000
 4
2 1 2 3
3 1 3 2
2 1 4 1
3 4 3 4

Problem Author: Sergey Pupyrev
Problem Source: The 11th Urals Collegiate Programing Championship, Ekaterinburg, April 21, 2007