func main()
	var h: int :: cui@inputInt()
	var w: int :: cui@inputInt()
	var k: int :: cui@inputInt()
	
	const mod: int :: 998244353
	
	var ans: int :: 0
	
	for i(1, k)
		var x: int :: cui@inputInt()
		var y: int :: cui@inputInt()
		var v: int :: cui@inputInt() % mod
		
		var num: int :: 0
		if(x > y)
			do num :+ y * (y + 1) / 2
			do num :+ y * (x - y)
			do num :+ (x - 1) * x / 2
		else
			do num :+ x * (x + 1) / 2
			do num :+ (x - 1) * x / 2
		end if
		
		var p: int :: x - 1 - w + y
		if(p > 0)
			do num :- p * (p + 1) / 2
		end if
		
		do ans :+ v * num
		do ans :% mod
	end for
	
	do cui@print("\{ans}\n")
end func