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 <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <algorithm>
#include <map>
#include <set>
#include <stack>
#include <vector>
#include <queue>
#include <string>
#include <complex>
using namespace std;

#define rep(i,n) for(int i=0; i<n; i++)
#define repa(i,s,e) for(int i=s; i<=e; i++)
#define repd(i,s,e) for(int i=s; i>=e; i--)

typedef long long ll;
typedef vector<int> vi;

int dxo[6] = { -1,  0, -1, 1, -1, 0};
int dxe[6] = { 0,  1, -1, 1, 0, 1};
int dy[6] = {-1, -1,  0, 0,  1, 1}; 

struct node { int x, y, dist, num; };

const int INF = 1000000009;
const int MAX_N = 101;
const int MAX_S = 11;
int n, m, s, t;
int cx[MAX_S], cy[MAX_S], tx[MAX_S], ty[MAX_S];
int field[MAX_N][MAX_N];
int dist[MAX_N][MAX_N];
char used[MAX_N][MAX_N];

int bfs(int x, int y) {
	rep(j,n) rep(i,m) used[i][j] = 0;

	int res = 0;
	queue<node> que;
	node md = {x, y, 0, -1};
	que.push(md);
	while(!que.empty()) {
		node nd = que.front();
		que.pop();

		if(dist[nd.x][nd.y] <= nd.dist) continue;

		used[nd.x][nd.y] = 1;
		res++;
		rep(k,6) {
			int xx = (nd.y % 2 == 0) ?  nd.x + dxo[k] : nd.x + dxe[k];
			int yy = nd.y + dy[k];
			if(xx >= 0 && yy >= 0 && xx < m && yy < n && used[xx][yy] == 0) {
				node nnd = {xx, yy, nd.dist+1, -1};
				que.push(nnd);
			}
		}
	}
	return res;
}

void solve() {
	rep(y,n) {
		rep(x,m) {
			field[x][y] = 0;
			dist[x][y] = INF;
		}
	}

	queue<node> que;
	rep(i,s) {
		node nd = { cx[i]-1, cy[i]-1, 0, i+1 };
		field[cx[i]-1][cy[i]-1] = i+1;
		dist[cx[i]-1][cy[i]-1] = 0;
		que.push(nd);
	}

	while(!que.empty()) {
		node nd = que.front();
		que.pop();

		rep(k,6) {
			int xx = (nd.y % 2 == 0) ?  nd.x + dxo[k] : nd.x + dxe[k];
			int yy = nd.y + dy[k];
			if(xx >= 0 && yy >= 0 && xx < m && yy < n) {
				if(dist[xx][yy] > nd.dist + 1) {
					dist[xx][yy] = nd.dist + 1;
					field[xx][yy] = nd.num;
				} else if(dist[xx][yy] == nd.dist + 1 && field[xx][yy] != nd.num) {
					field[xx][yy] = 0;
				} else {
					continue;
				}

				node nnd = { xx, yy, nd.dist+1, nd.num };
				que.push(nnd);
			}
		}
	}

	int maxval = 0;
	rep(i,t) {
		int res = bfs(tx[i]-1, ty[i]-1);
		maxval = max(res, maxval);
	}
	printf("%d\n", maxval);
}

int main() {
	for(;;) {
		scanf("%d", &m);
		if(m == 0) break;

		scanf("%d", &n);
		scanf("%d", &s);
		rep(i,s) scanf("%d%d", &cx[i], &cy[i]);

		scanf("%d", &t);
		rep(i,t) scanf("%d%d", &tx[i], &ty[i]);

		solve();
	}
}

C++: #include <iostream>
#include <cstring>
#include <set>
using namespace std;
int map[100][100];
const int evennext[6][2] = {
  {-1,-1},{0,-1},{-1,0},{1,0},{-1,1},{0,1},
};
const int oddnext[6][2] = {
  {0,-1},{1,-1},{-1,0},{1,0},{0,1},{1,1},
};
int m,n;
void paint(int d,int x,int y)
{
  if(map[y][x] <= d) return;
  map[y][x] = d;
  const int (*np)[2] = (y % 2 == 0) ? evennext : oddnext;
  for(int i=0; i<6; i++){
    int nx = x + np[i][0];
    int ny = y + np[i][1];
    if(0 <= nx && nx < m && 0 <= ny && ny < n){
      paint(d+1,nx,ny);
    }
  }
  return;
}
void count(int d,int x,int y,set<pair<int,int> > &memo)
{
  if(map[y][x] <= d) return;
  const int (*np)[2] = (y % 2 == 0) ? evennext : oddnext;
  if(!memo.insert(make_pair<int,int>(x,y)).second) return;
  for(int i=0; i<6; i++){
    int nx = x + np[i][0];
    int ny = y + np[i][1];
    if(0 <= nx && nx < m && 0 <= ny && ny < n){
      count(d+1,nx,ny,memo);
    }
  }
  return;
}
int main()
{
  for(;;){
    cin >> m;
    if(m == 0) break;
    cin >> n;
    for(int i=0; i<n; i++){
      for(int j=0; j<m; j++){
        map[i][j] = 500;
      }
    }
    int s;
    cin >> s;
    for(int i=0; i<s; i++){
      int x,y;
      cin >> x >> y;
      paint(0,x-1,y-1);
    }
    /*
    for(int i=0; i<n; i++){
      for(int j=0; j<m; j++){
        cout << " " << map[i][j];
      }
      cout << endl;
    }
    */
    int t;
    cin >> t;
    int max = 0;
    for(int i=0; i<t; i++){
      int x,y;
      cin >> x >> y;
      set<pair<int,int> > memo;
      count(0,x-1,y-1,memo);
      if(max < memo.size()) max = memo.size();
    }
    cout << max << endl;
  }
  return 0;
}