Max Valid Expression in Puzzle Matrix

An expression starts at any digit cell and can only go straight right or straight down, without turning. The characters must alternate as digit, +/-, digit; a single digit is also a valid expression. Find the maximum value of a valid path expression.

输入格式

h,w (1..100, hw≤10000); the character matrix contains only digits, +, and −, with at least one digit. The size limits are site supplements.

输出格式

Output the maximum value.

样例 1

输入：

1 5
9-1+8

输出：

16

样例 2

输入：

5 1
8
+
9
+
9

输出：

26

样例 3

输入：

2 3
1+2
3-4

输出：

4