Pascal Library

Time Limit: 1000 ms Memory Limit: 65536 KiB

Problem Description

Pascal University, one of the oldest in the country, needs to renovate its Library Building, because after all
these centuries the building started to show the effects of supporting the weight of the enormous amount of
books it houses.
To help in the renovation, the Alumni Association of the University decided to organize a series of
fund-raising dinners, for which all alumni were invited. These events proved to be a huge success and several
were organized during the past year. (One of the reasons for the success of this initiative seems to be the fact
that students that went through the Pascal system of education have fond memories of that time and would
love to see a renovated Pascal Library.)
The organizers maintained a spreadsheet indicating which alumni participated in each dinner. Now they want
your help to determine whether any alumnus or alumna took part in all of the dinners.
 

Input

 The input contains several test cases. The first line of a test case contains two integers N and D indicating
respectively the number of alumni and the number of dinners organized (1 N 100 and 1 D 500) .
Alumni are identified by integers from 1 to N . Each of the next D lines describes the attendees of a dinner,
and contains N integers Xi indicating if the alumnus/alumna i attended that dinner (Xi = 1) or not (Xi = 0) . The
end of input is indicated by N = D = 0 .
 

Output

 For each test case in the input your program must produce one line of output, containing either the word
`yes\', in case there exists at least one alumnus/alumna that attended all dinners, or the word `no\' otherwise.
Note:
Alumna: a former female student of a particular school, college or university.
Alumnus: a former male student of a particular school, college or university.
Alumni: former students of either sex of a particular school, college or university.
 

Sample Input

3 3
1 1 1
0 1 1
1 1 1
7 2
1 0 1 0 1 0 1
0 1 0 1 0 1 0
0 0

Sample Output

yes
no

Hint

 

Source

Latin America - South America - 2005/2006