const SIZE = 100;
var
n, m, p, count, ans, x, y, i, j : integer;
a : array[1..SIZE, 1..SIZE] of integer;
procedure colour(x, y : integer);
begin inc(count); a[x][y] := 1;
if (x > 1) and (a[x-1][y] = 0) then colour(x-1, y);
if (y > 1) and (a[x][y-1] = 0) then
colour(x, y-1);
if (x < n) and (a[x+1][y] = 0) then colour(x+1, y);
if (y < m) and (a[x][y+1] = 0) then
colour(x, y+1);
end;
begin
fillchar(a, sizeof(a), 0);
readln(n, m, p); for i := 1 to p do begin
read(x, y);
a[x][y] := 1;
end;
ans := 0;
for i := 1 to n do
for j := 1 to m do
if a[i][j] = 0 then begin
count := 0;
colour(i, j);
if (ans < count) then ans := count;
end;
writeln(ans);
end.
输入：
6 5 9
1 4
2 3
2 4
3 2
4 1
4 3
4 5
5 4
6 4
输出：7