n = gets.to_i
judge = Array.new(n,1)
n.times{
 array = gets.chomp.split(" ")
 array.each_with_index{|a,idx|
  if a != "-" && a != "nyanpass"
   judge[idx] = 0
  end
 }
}
if judge.count(1) == 1
 print judge.index(1) + 1
else
 print -1
end