v = Array.new(gets.to_i, 0)
while l=gets
    l.chomp.split.each_with_index do |g,i|
        v[i] += 1 if g == "nyanpass"
    end
end

if v.count {|i| i == v.length - 1 } == 1
    puts v.index(v.length - 1) + 1
else
    puts -1
end