h,w,*a=$<.read.split.map &:to_i;b=[]
(h*w).times{|i|x=a.shift;s=1<<i;b.each{|y,t|x^y<x&&(x^=y;s^=t)};x>0&&b<<[x,s]}
a[1..].each{|x|s=0;b.each{|y,t|x^y<x&&(x^=y;s^=t)};r=[];x<1&&(r=s>0?[]:[0,1]*2;c=0;(0...h*w).select{s[_1]>0}.chunk{_1/w}.each{|i,v|q=i*w+c;r<<q;r+=v-[q];s[q]<1&&r<<q;c=r[-1]%w});puts r.size-1,r.map{[_1/w+1,_1%w+1]*' '}}