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 <map>
#include <queue>
#include <climits>

using namespace std;

const int e_dx[] = {0, 1, 1, 1, 0, -1};
const int e_dy[] = {-1, -1, 0, 1, 1, 0};
const int o_dx[] = {-1, 0, 1, 0, -1, -1};
const int o_dy[] = {-1, -1, 0, 1, 1, 0};;

int m, n;
int place[102][102];

class state {
public:
    int x, y;
    int cnt;
    state(int a, int b, int c) { x = a; y = b; cnt = c; }
};

void init()
{
    for (int y = 1; y <= n; y++)
        for (int x = 1; x <= m; x++)
            place[y][x] = INT_MAX;

    int s;
    cin >> s;
    for (int i = 0; i < s; i++) {
        int x, y;

        cin >> x >> y;
        place[y][x] = 0;
        state s(x, y, 0);
        queue<state> q;
        q.push(s);

        while (!q.empty()) {
            state now = q.front();
            q.pop();

            for (int i = 0; i < 6; i++) {
                int nx, ny;
                if (now.y % 2) {
                    nx = now.x + o_dx[i];
                    ny = now.y + o_dy[i];
                }
                else {
                    nx = now.x + e_dx[i];
                    ny = now.y + e_dy[i];
                }

                if (nx < 1 || nx > m || ny < 1 || ny > n)
                    continue;
                if (now.cnt + 1 < place[ny][nx]) {
                    place[ny][nx] = now.cnt + 1;
                    state tmp(nx, ny, now.cnt + 1);
                    q.push(tmp);
                }
            }
        }
    }
}


void bfs()
{
    int t;
    int ans = 0;

    cin >> t;
    while (t--) {
        int p, q;
        map<pair<int, int>, bool > ma;
        int num = 0;

        cin >> p >> q;
        state s(p, q, 0);
        queue<state> qu;
        ma[pair<int, int>(p, q)] = true;
        qu.push(s);

        while (!qu.empty()) {
            state now = qu.front();
            qu.pop();

            for (int i = 0; i < 6; i++) {
                int nx, ny;
                if (now.y % 2) {
                    nx = now.x + o_dx[i];
                    ny = now.y + o_dy[i];
                }
                else {
                    nx = now.x + e_dx[i];
                    ny = now.y + e_dy[i];
                }

                if (nx < 1 || nx > m || ny < 1 || ny > n)
                    continue;
                if (ma.count(pair<int, int>(nx, ny)) != 0)
                    continue;
                if (now.cnt + 1 < place[ny][nx]) {
                    num++;
                    state tmp(nx, ny, now.cnt + 1);
                    qu.push(tmp);
                    ma[pair<int, int>(nx, ny)] = true;
                }
            }
        }
        ans = max(ans, num + 1);
    }
    cout << ans << endl;
}

int main()
{
    while (cin >> m >> n, m) {
        init();        
        bfs();
    }

    return 0;
}

C++: #include<iostream>
using namespace std;
int field[110][110],next[110][110];
int d[6][2] = {{1,0},{0,1},{-1,0},{0,-1},{1,1},{1,-1}};
int dd[6][2] = {{1,0},{0,1},{-1,0},{0,-1},{-1,-1},{-1,1}};
void near(int x, int y, int n);
int coun(int x, int y, int n);
int main(){
  int w,h,n,t;
  while(cin >>w,w){
    cin >>h;
    int shop[10][2],kou[10][2];
    int ans = 0;
    cin >>n; for(int i=0; i<n; i++){cin >>shop[i][0]>>shop[i][1];}
    cin >>t; for(int i=0; i<t; i++){cin >>kou[i][0]>>kou[i][1];}
    for(int i=0; i<110; i++){for(int j=0; j<110; j++){field[j][i] = -1;}}
    for(int i=1; i<=h; i++){for(int j=1; j<=w; j++){field[j][i] = 100;}}
    for(int i=0; i<n; i++){near(shop[i][0],shop[i][1],0);}
    for(int i=0; i<t; i++){
      for(int k=0; k<110; k++){for(int j=0; j<110; j++){next[j][k] = field[j][k];}}
      int r = coun(kou[i][0],kou[i][1],0);
      if(ans<r){ans = r;}
    }
    cout <<ans<<endl;
  }
  return 0;
}
void near(int x, int y, int n){
  field[x][y] = n;
  for(int i=0; i<6; i++){
    if(y%2 == 0){if(field[x+d[i][0]][y+d[i][1]] > n+1){near(x+d[i][0],y+d[i][1],n+1);}}
    else{if(field[x+dd[i][0]][y+dd[i][1]] > n+1){near(x+dd[i][0],y+dd[i][1],n+1);}}
  }
}
int coun(int x, int y, int n){
  int k = 1;
  next[x][y] = n;
  for(int i=0; i<6; i++){
    if(y%2 == 0){if(next[x+d[i][0]][y+d[i][1]] > n+1){k+=coun(x+d[i][0],y+d[i][1],n+1);}}
    else{if(next[x+dd[i][0]][y+dd[i][1]] > n+1){k+=coun(x+dd[i][0],y+dd[i][1],n+1);}}
  }
  return k;
}