n = gets.to_i
as = []
n.times do
  as << gets.split
end
bs = as.transpose
ans = []
bs.each_with_index do |b, i|
  if b.count('nyanpass') == n -1
    ans << i
  end
end
if ans.count == 1
  puts ans.first + 1
else
  puts -1
end