n=STDIN.gets.to_i

cs=Array.new(n,0)
n.times do |a|
	p1=0
	STDIN.gets.split(" ").each do |e|
		if e=="nyanpass" then
			cs[p1]+=1
		end
		p1+=1
	end
end
ans=-1
c=0
p1=1
cs.each do |e|
	if e==n-1 then
		ans=p1
		c+=1
	end
	p1+=1
end
if c==1 then
	puts ans
else
	puts -1
end