Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
	)

var scanner = bufio.NewScanner(os.Stdin)

const INF = 0x7FFFFFFF

var (
	direction1 = [][]int{ // 奇数段目の移動方向
		{-1, 0}, {1, 0}, {0, -1}, {0, 1}, {1, -1}, {1, 1},
	}
	direction2 = [][]int{ // 偶数段目の移動方向
		{-1, -1}, {0, -1}, {1, 0}, {0, 1}, {-1, 1}, {-1, 0},
	}
)

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		m, _ := strconv.Atoi(buf[0])
		n, _ := strconv.Atoi(buf[1])
		if m == 0 && n == 0 {
			break
		}
		// initialize district_map
		/*
			district_map = [
				[-1, -1,  -1,  -1,  -1]
				[-1, INF, INF, INF, -1]
				[-1, INF, INF, INF, -1]
				[-1, INF, INF, INF, -1]
				[-1, INF, INF, INF, -1]
				[-1, -1,  -1,  -1,  -1]
			]
		*/
		district_map := make([][]int, n+2)
		for i := range district_map {
			district_map[i] = make([]int, m+2)
		}
		tmp1 := make([]int, m+2)
		for i := range tmp1 {
			tmp1[i] = -1
		}
		district_map[0] = tmp1
		district_map[n+1] = tmp1
		for i := 1; i < n+1; i++ {
			district_map[i] = make([]int, m+2)
			district_map[i][0] = -1
			district_map[i][m+1] = -1
			for j := 1; j < m+1; j++ {
				district_map[i][j] = INF
			}
		}

		scanner.Scan()
		s, _ := strconv.Atoi(scanner.Text())
		for i := 0; i < s; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			x, _ := strconv.Atoi(buf_[0])
			y, _ := strconv.Atoi(buf_[1])
			Search(Point{x, y}, district_map, m, n)
		}
		ans := 0
		scanner.Scan()
		t, _ := strconv.Atoi(scanner.Text())
		for i := 0; i < t; i++ {
			scanner.Scan()
			buf__ := strings.Split(scanner.Text(), " ")
			x, _ := strconv.Atoi(buf__[0])
			y, _ := strconv.Atoi(buf__[1])
			z := Count(Point{x, y}, district_map, m, n)
			ans = max(ans, z)
		}
		fmt.Println(ans)
	}
}

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

type Point struct {
	x, y int
}

type Entry struct {
	hop   int
	point Point
}

func Search(p Point, mp [][]int, m, n int) {
	que := make([]Entry, 0)
	que = append(que, Entry{0, p})
	check := make([][]bool, n+2)
	for i := range check {
		check[i] = make([]bool, m+2)
	}
	check[p.y][p.x] = true
	mp[p.y][p.x] = 0
	var direction [][]int
	for len(que) > 0 {
		tmp := que[0]
		que = que[1:]
		dist, point := tmp.hop, tmp.point
		if point.y%2 == 0 {
			direction = direction1
		} else {
			direction = direction2
		}
		for _, d := range direction {
			nx, ny := point.x+d[0], point.y+d[1]
			if !check[ny][nx] && mp[ny][nx] != -1 {
				check[ny][nx] = true
				if mp[ny][nx] > dist+1 {
					mp[ny][nx] = dist + 1
				}
				que = append(que, Entry{dist + 1, Point{nx, ny}})
			}
		}
	}
}

func Count(p Point, mp [][]int, m, n int) int {
	que := make([]Entry, 0)
	que = append(que, Entry{0, p})
	check := make([][]bool, n+2)
	for i := range check {
		check[i] = make([]bool, m+2)
	}
	check[p.y][p.x] = true
	ans := 1
	var direction [][]int
	for len(que) > 0 {
		tmp := que[0]
		que = que[1:]
		dist, point := tmp.hop, tmp.point
		if point.y%2 == 0 {
			direction = direction1
		} else {
			direction = direction2
		}
		for _, d := range direction {
			nx, ny := point.x+d[0], point.y+d[1]
			if !check[ny][nx] && mp[ny][nx] != -1 {
				check[ny][nx] = true
				if mp[ny][nx] > dist+1 {
					ans++
				}
				que = append(que, Entry{dist + 1, Point{nx, ny}})
			}
		}
	}
	return ans
}

C++: #include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
using namespace std;

const int INF = 1 << 30;
const int dx[2][6] = { {0, -1, -1, -1, 0, 1}, {1, 0, -1, 0, 1, 1} };
const int dy[6] = {-1, -1, 0, 1, 1, 0};

class State
{
public:
  int x, y, c;
  State(int _x = 0, int _y = 0, int _c = 0)
    :x(_x), y(_y), c(_c) {}
};

int main()
{
  int m, n;
  while (cin >> m >> n) {
    if ((m|n) == 0)
      break;

    int s;
    cin >> s;
    vector<vector<int> > cost(n, vector<int>(m, INF));
    for (int i = 0; i < s; ++i) {
      int x, y;
      cin >> x >> y;
      queue<State> que;
      que.push(State(x-1, y-1, 0));
      while (!que.empty()) {
	const State st = que.front();
	que.pop();

	if (cost[st.y][st.x] < st.c)
	  continue;

	cost[st.y][st.x] = st.c;
	for (int d = 0; d < 6; ++d) {
	  x = st.x + dx[st.y%2][d];
	  y = st.y + dy[d];
	  if (x < 0 || m <= x || y < 0 || n <= y || cost[y][x] <= st.c+1)
	    continue;
	  cost[y][x] = st.c+1;
	  que.push(State(x, y, st.c+1));
	}
      }
    }

    int t;
    cin >> t;
    int ans = 0;
    for (int i = 0; i < t; ++i) {
      int x, y, cnt = 0;
      cin >> x >> y;
      queue<State> que;
      que.push(State(x-1, y-1, 0));
      vector<vector<int> > visited(n, vector<int>(m, 0));
      while (!que.empty()) {
	const State st = que.front();
	que.pop();

	if (cost[st.y][st.x] <= st.c || visited[st.y][st.x])
	  continue;

	++cnt;
	visited[st.y][st.x] = 1;
	for (int d = 0; d < 6; ++d) {
	  x = st.x + dx[st.y%2][d];
	  y = st.y + dy[d];
	  if (x < 0 || m <= x || y < 0 || n <= y || cost[y][x] <= st.c+1 || visited[y][x])
	    continue;
	  que.push(State(x, y, st.c+1));
	}
      }
      ans = max(ans, cnt);
    }

    cout << ans << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<queue>
#include<algorithm>

using namespace std;

typedef pair<int, int> P;
typedef pair<int, P> PP;

int m, n, s, t;//?¨????????????¢?¨??????????????????°?¨?????????°
int dis[100][100];//???????¨?
const int vx1[6] = { -1,-1,0,1,0,-1 };//?????????????\???°??¨???????????¶??°??¨
const int vx2[6] = { -1,0,1,1,1,0 };//??????????????¶??°??¨??????????\???°??¨
const int vy[6] = { 0,-1,-1,0,1,1 };
P store[10], plan[10];

void bfs() {
	queue<PP> q;//???????????????y??§?¨????x??§?¨?
	for (int i = 0; i < s; i++) {
		q.push(make_pair(0, make_pair(store[i].first, store[i].second)));
		dis[store[i].first][store[i].second] = -1;//?????§???????????¨?????????-1??¨??????
	}
	while (q.size()) {
		int ct = q.front().first;
		P tmp = q.front().second;
		q.pop();
		for (int i = 0; i < 6; i++) {
			int fy = tmp.first, fx = tmp.second;
			if (fy % 2)fx += vx2[i];
			else fx += vx1[i];
			fy += vy[i];
			if (fy < 0 || fy >= n || fx < 0 || fx >= m)continue;
			if (dis[fy][fx] == 0) {
				dis[fy][fx] = ct + 1;
				q.push(make_pair(ct + 1, make_pair(fy, fx)));
			}
		}
	}
}

int bfs2(int a) {
	int ans = 1;
	queue<PP> q;
	q.push(make_pair(0, plan[a]));
	bool islook[100][100] = {};
	bool f = false;
	for (int i = 0; i < s; i++) {
		if (plan[a] == store[i])f = true;
	}
	if (f)return 0;
	islook[q.front().second.first][q.front().second.second] = true;
	while (q.size()) {
		P tmp = q.front().second;
		int ct = q.front().first;
		q.pop();
		for (int i = 0; i < 6; i++) {
			int fy = tmp.first, fx = tmp.second;
			if (fy % 2)fx += vx2[i];
			else fx += vx1[i];
			fy += vy[i];
			if (fy < 0 || fy >= n || fx < 0 || fx >= m)continue;
			if (!islook[fy][fx] && dis[fy][fx] - ct > 1) {
				ans++;
				islook[fy][fx] = true;
				q.push(make_pair(ct + 1, make_pair(fy, fx)));
			}
		}
	}
	return ans;
}

int main() {
	while (cin >> m >> n, m * n) {
		cin >> s;
		for (int i = 0; i < s; i++) {
			cin >> store[i].second >> store[i].first;
			store[i].first--, store[i].second--;
		}
		cin >> t;
		for (int i = 0; i < t; i++) {
			cin >> plan[i].second >> plan[i].first;
			plan[i].first--, plan[i].second--;
		}
		bfs();//?????????????????????????????¢?????¬???
		int ans = 0;
		for (int i = 0; i < t; i++) {
			ans = max(bfs2(i), ans);//??¨????£???°?????????
		}
		cout << ans << endl;
		for (int i = 0; i < n; i++)for (int j = 0; j < m; j++)dis[i][j] = 0;
	}
	return 0;
}