#!/usr/bin/env luajit
require("utils")

local hm = {}
for line in io.lines(arg[3]) do
	local row = {}
	for c in chars(line) do
		table.insert(row, tonumber(c))
	end
	table.insert(hm, row)
end

local function get(r, c)
	return (hm[r] or {})[c] or math.huge
end

local lowsum = 0
for r, row in pairs(hm) do
	for c, col in pairs(row) do
		if col < get(r - 1, c) and col < get(r, c - 1) and col < get(r + 1, c) and col < get(r, c + 1) then
			lowsum = lowsum + col + 1
		end
	end
end

print(lowsum)