h = Hash.new{|h, k| h[k] = {}}
n = gets.to_i
if n == 0
   puts "inabameguru"
   exit
end
n.times do
    str = gets.strip
    str.length.times do |i|
        h[i][str[i]] = true
    end
end
s = ["a", "i", "u", "e", "n", "b", "m", "g", "r"]
ki = -1
kc = ""
h.length.times do |i|
    s.each do |c|
        if h[i][c] == nil
            ki = i
            kc = c
            break
        end
    end
    break if ki != -1
end
if ki != -1
    b = "inabameguru"
    bc = b[ki]
    if bc == kc
        puts b
        exit
    end
    h2 = {}
    h2["a"] = true; h2["i"] = true; h2["u"] = true; h2["e"] = true
    h2["b"] = false; h2["g"] = false; h2["m"] = false; h2["r"] = false; h2["n"] = false
    if (h2[bc] && !h2[kc]) || (!h2[bc] && h2[kc])
        b = "nabamegurui"
    end
    b.length.times do |i|
        if (h2[b[i]] == h2[kc]) && b[i] == kc
            b[i], b[ki] = b[ki], b[i]
            puts b
            exit
        end
    end
else
    puts "NO"
end