inputs = []

inputs.push(gets.split)

h = inputs[0][0].to_i
w = inputs[0][1].to_i

h.times { inputs.push(gets.split) }

data = []
for i in 0...h do
    data += inputs[i + 1]
end

data.sort!

for j in 0...h do
    for i in 0...w do
        print data[j * w + i].to_s + ' '
    end
    puts "\n"
end