A satellite map of an archipelago is an R-by-C binary grid where 1 is land and 0 is sea. A landmass is a maximal group of land cells connected to one another through shared edges (up, down, left, or right; diagonal touches do not connect).
Report the number of cells in the largest landmass. If there is no land at all, report 0.
Input format
Line 1: two integers R and C.
Next R lines: each contains C space-separated integers, each 0 or 1.
Output format
A single integer: the cell count of the largest 4-connected landmass, or 0 if there is none.
Constraints
- 1 <= R, C <= 200
- Each cell is 0 or 1.