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<vector>
#include<queue>
#include<tuple>
#include<set>
#include<algorithm>
using namespace std;

const int INF = 100000;

class Node {
public:
    int y, x, depth;
    Node(int y, int x, int d) :y(y), x(x), depth(d) {}
};

typedef tuple<int, int> Point;

enum {EVEN, ODD};
enum {Y, X};
const int NEXT[2][6][2] = {
    {
        {0, -1},
        {-1, -1},
        {-1, 0},
        {0, 1},
        {1, -1},
        {1, 0},
    },
    {
        {0, -1},
        {-1, 0},
        {-1, 1},
        {0, 1},
        {1, 0},
        {1, 1},
    },
};

void init(vector<vector<int>>& hex, int y, int x) {
    int h = hex.size(), w = hex[0].size();
    queue<Node> q;
    q.push(Node(y, x, 0));
    while(!q.empty()) {
        Node current = q.front();
        q.pop();
        if(hex[current.y][current.x] <= current.depth) continue;
        hex[current.y][current.x] = current.depth;
        for(const auto& d: NEXT[y & 1]) {
            int ny = current.y + d[Y];
            int nx = current.x + d[X];
            if(ny < 0 || h <= ny) continue;
            if(nx < 0 || w <= nx) continue;
            q.push(Node(ny, nx, current.depth + 1));
        }
    }
}

int bfs(const vector<vector<int>>& hex, int y, int x) {
    int h = hex.size(), w = hex[0].size();
    int result = 0;
    set<Point> visited;
    queue<Node> q;
    q.push(Node(y, x, 0));
    while(!q.empty()) {
        Node current = q.front();
        q.pop();
        if(visited.count(Point(current.y, current.x))) continue;
        visited.insert(Point(current.y, current.x));
        if(hex[current.y][current.x] <= current.depth) continue;
        ++result;
        for(const auto& d: NEXT[y & 1]) {
            int ny = current.y + d[Y];
            int nx = current.x + d[X];
            if(ny < 0 || h <= ny) continue;
            if(nx < 0 || w <= nx) continue;
            q.push(Node(ny, nx, current.depth + 1));
        }
    }
    return result;
}

int main() {
    int m, n;
    int s, t;
    while(cin >> m >> n, m | n) {
        vector<vector<int>> hex(n, vector<int>(m, INF));
        for(cin >> s; s > 0; --s) {
            int x, y;
            cin >> x >> y;
            init(hex, y - 1, x - 1);
        }
        int answer = 0;
        for(cin >> t; t > 0; --t) {
            int x, y;
            cin >> x >> y;
            answer = max(answer, bfs(hex, y - 1, x - 1));
        }
        cout << answer << endl;
    }
}

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;//????????????????????§?¨?????????§?¨?
	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 fx = tmp.first, fy = tmp.second;
			if (fx % 2)fy += vx2[i];
			else fy += vx1[i];
			fx += vy[i];
			if (fx < 0 || fx >= n || fy < 0 || fy >= m)continue;
			if (!dis[fx][fy]) {
				dis[fx][fy] = ct + 1;
				q.push(make_pair(ct + 1, make_pair(fx, fy)));
			}
		}
	}
}

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