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 <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <algorithm>
#include <utility>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <functional>

using namespace std;

#define fst first
#define scd second
#define PB push_back
#define MP make_pair
#define chmin(a,b) a=min(a,b)
#define chmax(a,b) a=max(a,b)
#define rep(i,x) for(int i=0;i<(int)(x);++i)
#define rep1(i,x) for(int i=1;i<=(int)(x);++i)
#define rrep(i,x) for(int i=(x)-1;i>=0;--i)
#define rrep1(i,x) for(int i=(x);i>=1;--i)
#define FOR(i,a,x) for(int i=(a);i<(x);++i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()

template<typename T> T get(){T a;cin >> a;return a;}
template<typename T> T rev(T & a){reverse(all(a));return a;}

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;

const int inf = 1e9;
const ll linf = 3e18;

class coord {
    public:
        int x, y;
        coord(int x0, int y0){x=x0;y=y0;};
};

int dx[2][6] = {{0, -1, 0, 1, 1, 1}, {-1, -1, -1, 0, 1, 0}};
int dy[6] = {-1, 0, 1, 1, 0, -1};

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int H, W;
    while (cin >> H >> W, H || W) {
        vector<vector<pii> > mp(H+1, vector<pii>(W+1, MP(0, inf)));

        int s; cin >> s;

        rep1(i, s) {
            int x, y; cin >> x >> y;

            queue<coord> q;
            q.push(coord(x, y));
            mp[y][x] = MP(i, 0);

            while (q.size()) {
                coord crd = q.front(); q.pop();
                rep(j, 6) {
                    int ny = crd.y + dy[j], nx = crd.x + dx[crd.y % 2][j];
                    if (ny < 1 || ny > H || nx < 1 || nx > W) continue;
                    if (mp[ny][nx].fst == i) continue;
                    if (mp[ny][nx].scd < mp[crd.y][crd.x].scd + 1) continue;
                    if (mp[ny][nx].scd == mp[crd.y][crd.x].scd + 1) {
                        mp[ny][nx].fst = -1;
                        continue;
                    }
                    mp[ny][nx] = MP(i, mp[crd.y][crd.x].scd + 1);
                    q.push(coord(nx, ny));
                }
            }
        }

        int ma = 0;

        int t; cin >> t;

        rep1(i, t) {
            int cnt = 1;

            vector<vector<pii> > tmp = mp;
            int x, y; cin >> x >> y;

            queue<coord> q;
            q.push(coord(x,y));
            mp[y][x] = MP(0, 0);

            while (q.size()) {
                coord crd = q.front(); q.pop();
                rep(j, 6) {
                    int ny = crd.y + dy[j], nx = crd.x + dx[y % 2][j];
                    if (ny < 1 || ny > H || nx < 1 || nx > W) continue;
                    if (mp[ny][nx].fst == 0) continue;
                    if (mp[ny][nx].scd < mp[crd.y][crd.x].scd + 1) continue;
                    if (mp[ny][nx].scd == mp[crd.y][crd.x].scd + 1) {
                        mp[ny][nx].fst = -1;
                        continue;
                    }
                    mp[ny][nx] = MP(0, mp[crd.y][crd.x].scd + 1);
                    q.push(coord(nx, ny));
                    cnt++;
                }
            }

            chmax(ma, cnt);

            mp = tmp;
        }

        cout << ma << endl;
    }
}

C++: #include <cstdio>
#include <cstring>
#include <queue>
#include <utility>
#include <algorithm>
using namespace std;
typedef pair<int,int> _P;
typedef pair<_P,int> P;
int color[100][100],tmp[100][100];
bool vst[100][100];
int dx0[]={0,1,0,-1,-1,-1},dy0[]={-1,0,1,1,0,-1};
int dx1[]={1,1,1,0,-1,0},dy1[]={-1,0,1,1,0,-1};
int m,n;
int coloring(int color[100][100],int x,int y) {
	memset(vst,0,sizeof(vst));
	queue<P> Q;
	Q.push(P(_P(x,y),0));
	vst[x][y]=true;
	int sum=0;
	while(!Q.empty()) {
		P p=Q.front();Q.pop();
		_P _p=p.first;
		if(color[_p.first][_p.second]<=p.second) continue;
		color[_p.first][_p.second]=p.second;
		sum++;
		int *dx,*dy;
		if(_p.second&1) dx=dx1,dy=dy1;
		else dx=dx0,dy=dy0;
		for(int i=0;i<6;i++) {
			int nx=_p.first+dx[i],ny=_p.second+dy[i];
			if(0>nx||nx>=m||0>ny||ny>=n)continue;
			if(vst[nx][ny])continue;
			vst[nx][ny]=true;
			Q.push(P(_P(nx,ny),p.second+1));
		}
	}
	return sum;
}
int main() {
	int s,t,x,y;
	while(scanf("%d",&m),m) {
		scanf("%d",&n);
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++)color[j][i]=1<<30;
		}
		scanf("%d",&s);
		for(int i=0;i<s;i++) {
			scanf("%d %d",&x,&y);
			coloring(color,x-1,y-1);
		}
		scanf("%d",&t);
		int ans=0;
		for(int i=0;i<t;i++) {
			scanf("%d %d",&x,&y);
			memcpy(tmp,color,sizeof(color));
			ans=max(ans,coloring(tmp,x-1,y-1));
		}
		printf("%d\n",ans);
	}
}