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 <algorithm>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <vector>

using namespace std;

#define reps(i,f,n) for(int i=f; i<int(n); ++i)
#define rep(i,n) reps(i,0,n)

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

const int INF = 1001001001;

int dist(pii a, pii b)
{
	int dy = a.first - b.first;
	int dx = a.second - b.second;
	if(0 <= dy*dx){
		dy = abs(dy);
		dx = abs(dx);
		return dy + max(0, dx - (dy+1-min(a.first,b.first)%2)/2);
	}
	else{
		dy = abs(dy);
		dx = abs(dx);
		return dy + max(0, dx - (dy + min(a.first, b.first)%2)/2);
	}
}

int main()
{
	int m, n;
	while(scanf("%d%d", &m, &n), m){
		int s;
		scanf("%d", &s);
		pii conv[10];
		rep(i, s)
			scanf("%d%d", &conv[i].second, &conv[i].first);
		
		int d[101][101];
		rep(i, n) rep(j, m){
			d[i+1][j+1] = INF;
			rep(k, s)
				d[i+1][j+1] = min(d[i+1][j+1], dist(pii(i+1, j+1), conv[k]));
		}
		
		int t, ans = 0;
		scanf("%d", &t);
		rep(i, t){
			int x, y;
			scanf("%d%d", &x, &y);
			
			int cnt = 0;
			rep(j, n) rep(k, m)
				cnt += dist(pii(j+1, k+1), pii(y, x)) < d[j+1][k+1];
			ans = max(ans, cnt);
		}
		printf("%d\n", ans);
	}
	return 0;
}

C++: #include <iostream>
#include <vector>

using namespace std;

int dist(int x1,int y1,int x2,int y2)
{
	if(y1>y2){
		swap(x1,x2);
		swap(y1,y2);
	}
	
	int dy=y2-y1;
	if(y1&1)
		return max(max(x2-x1-dy/2,x1-x2-(dy+1)/2),0)+dy;
	else
		return max(max(x2-x1-(dy+1)/2,x1-x2-dy/2),0)+dy;
}

int main()
{
	for(int w,h;cin>>w>>h;){
		int s; cin>>s;
		vector<int> xs(s),ys(s);
		for(int i=0;i<s;i++)
			cin>>xs[i]>>ys[i];
		int t; cin>>t;
		int res=0;
		while(t--){
			int x,y; cin>>x>>y;
			int tmp=0;
			for(int i=1;i<=h;i++){
				for(int j=1;j<=w;j++){
					int d=1<<29;
					for(int k=0;k<s;k++)
						d=min(d,dist(xs[k],ys[k],j,i));
					if(d>dist(x,y,j,i))
						tmp++;
				}
			}
			res=max(tmp,res);
		}
		cout<<res<<endl;
	}
	
	return 0;
}

C++: #include<queue>
#include<cstdio>

#define	mp	make_pair

using namespace std;

typedef	pair<int,int>	pii;

const int dx[2][6]={{1,0,-1,-1,-1,0},{1,1,0,-1,0,1}};
const int dy[6]={0,-1,-1,0,1,1};
int dis[100][100];
bool land[100][100];

int main(){
	for(int m,n;scanf("%d%d",&n,&m),n;){
		for(int i=0;i<m;i++)for(int j=0;j<n;j++)	land[i][j]=false,dis[i][j]=1<<30;

		int s;	scanf("%d",&s);
		for(int i=0;i<s;i++){
			int px,py;	scanf("%d%d",&px,&py);
			px--,py--;
			land[py][px]=true;

			dis[py][px]=0;
			queue<pii> qu;	qu.push(mp(py,px));
			while(!qu.empty()){
				pii a=qu.front();	qu.pop();
				int y=a.first,x=a.second;
				for(int k=0;k<6;k++){
					int yy=y+dy[k],xx=x+dx[y%2][k];
					if(0<=yy && yy<m && 0<=xx && xx<n){
						if(dis[y][x]+1<dis[yy][xx]){
							qu.push(mp(yy,xx));
							dis[yy][xx]=dis[y][x]+1;
						}
					}
				}
			}
		}

		int t,ans=0;	scanf("%d",&t);
		while(t--){
			static int tmp[100][100];
			for(int i=0;i<m;i++)for(int j=0;j<n;j++)	tmp[i][j]=1<<30;

			int px,py;	scanf("%d%d",&px,&py);
			px--,py--;
			if(dis[py][px]==0)	continue;

			int cnt=0;
			tmp[py][px]=0;
			queue<pii> qu;	qu.push(mp(py,px));
			while(!qu.empty()){
				pii a=qu.front();	qu.pop();
				int y=a.first,x=a.second;
				cnt++;
				for(int k=0;k<6;k++){
					int yy=y+dy[k],xx=x+dx[y%2][k];
					if(0<=yy && yy<m && 0<=xx && xx<n){
						if(tmp[y][x]+1<tmp[yy][xx] && tmp[y][x]+1<dis[yy][xx]){
							qu.push(mp(yy,xx));
							tmp[yy][xx]=tmp[y][x]+1;
						}
					}
				}
			}

			ans=max(ans,cnt);
		}

		printf("%d\n",ans);
	}

	return 0;
}