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};
	used[x][y] = 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 && dist[xx][yy] > nd.dist + 1) {
				node nnd = {xx, yy, nd.dist+1, -1};
				used[xx][yy] = 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 };
		que.push(nd);
	}

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

		if(dist[nd.x][nd.y] > nd.dist) {
			dist[nd.x][nd.y] = nd.dist;
			field[nd.x][nd.y] = nd.num;
		} else if(dist[nd.x][nd.y] == nd.dist && field[nd.x][nd.y] != nd.num && field[nd.x][nd.y] != 0) {
			field[nd.x][nd.y] = 0;
		} else {
			continue;
		}

		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) {
				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 <cmath>
using namespace std;

#define REP(i,n) for(int i=1; i<=n; i++)

#define INF (1<<20)
int field[128][128];

int dist(int x1, int y1, int x2, int y2)
{
	x1-=(y1-1)/2;
	x2-=(y2-1)/2;

	return (abs(x1-x2)+abs(y1-y2)+abs((x1+y1)-(x2+y2)))/2;
}

int main()
{
	int w,h,n,x0,y0,cnt,ans;
	while(cin >> w, w)
	{
		cin >> h;
		REP(y,h)REP(x,w)
		{
			field[y][x] = INF;
		}
		
		cin >> n;
		while(n--)
		{
			cin >> x0 >> y0;
			REP(y,h)REP(x,w)
			{
				field[y][x] = min(field[y][x],dist(x0,y0,x,y));
			}
		}

		ans = 0;
		cin >> n;
		while(n--)
		{
			cnt = 0;
			cin >> x0 >> y0;
			REP(y,h)REP(x,w)
			{
				if(field[y][x]>dist(x0,y0,x,y)) cnt++;
			}
			ans = max(ans,cnt);
		}

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