N, M = gets.split.map(&:to_i)
A = N.times.map { gets.split.map(&:to_i) }

if N == 1
  puts 0
  exit
end

dp = Array.new(N) { Array.new(M, Float::INFINITY) }

N.times do |i|
  if i == 0
    M.times do |j|
      dp[i][j] = A[i][j]
    end
  else
    min_v = Float::INFINITY

    M.times do |j|
      dp[i][j] = dp[i - 1][j] + A[i][j]
      min_v = dp[i][j] if min_v > dp[i][j]
    end

    M.times do |j|
      nv = min_v + A[i][j]
      dp[i][j] = nv if dp[i][j] > nv
    end
  end
end

puts dp[N - 1].min