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 <queue>
#include <algorithm>
#include <map>
#include <set>

using namespace std;
const int N = 100;
const int INF = 100000000;
typedef pair<int, int> P;

class State{
public:
  int x, y, cost;
  State(int y, int x, int cost) : y(y), x(x), cost(cost) {}
};

int w, h, s, t;
int dist[11][N][N];
int dy[2][6] = {{-1, -1, 0, 1, 1, 0},{-1, -1, 0, 1, 1, 0}};
int dx[2][6] = {{-1, 0, 1, 0, -1, -1},{0, 1, 1, 1, 0, -1}};
vector<P> cs;

void bfs(int sy, int sx, int p){
  for(int i=0;i<h;i++) for(int j=0;j<w;j++) dist[p][i][j] = INF;
  queue<State> que;
  que.push(State(sy, sx, 0));
  dist[p][sy][sx] = 0;
  while(!que.empty()){
    State u = que.front(); que.pop();
    for(int i=0;i<6;i++){
      int ny = u.y + dy[u.y%2][i];
      int nx = u.x + dx[u.y%2][i];
      if(ny<0 || ny>=h) continue;
      if(nx<0 || nx>=w) continue;
      if(dist[p][ny][nx] != INF) continue;
      dist[p][ny][nx] = u.cost+1;
      que.push(State(ny, nx, u.cost+1));
    }
   }
}

int solve(){
  int res = 0;
  bfs(cs[s].first, cs[s].second, s);
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      bool f = false;
      int valm = INF, col;
      for(int k=0;k<=s;k++){
        if(valm > dist[k][i][j]){
          f = false;
          valm = dist[k][i][j];
          col = k;
        }else if(valm == dist[k][i][j]) f = true;
      }
      if(!f && col == s) res++;
    }
  }
  return res;
}

main(){
  while(cin >> w >> h && (w|h)){
    cs.clear();
    int x, y;
    cin >> s;
    for(int i=0;i<s;i++){
      cin >> x >> y;
      cs.push_back(P(y-1, x-1));
    }
    for(int i=0;i<cs.size();i++) bfs(cs[i].first, cs[i].second, i);
    int ans = 0;
    cin >> t;
    for(int i=0;i<t;i++){
      cin >> x >> y;
      cs.push_back(P(y-1, x-1));
      ans = max(ans, solve());
      cs.pop_back();
    }
    cout << ans << endl;
  }
}

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

using namespace std;

inline 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;scanf("%d%d",&w,&h),w;){
		int s; scanf("%d",&s);
		vector<int> xs(s),ys(s);
		for(int i=0;i<s;i++)
			scanf("%d%d",&xs[i],&ys[i]);
		int t; scanf("%d",&t);
		int res=0;
		while(t--){
			int x,y; scanf("%d%d",&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);
		}
		printf("%d\n",res);
	}
	
	return 0;
}

C++: #include <iostream>
#include <sstream>
#include <fstream>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <cmath>
using namespace std;

typedef pair <int, int> PII;
typedef PII Node;
typedef queue <Node> Queue;

typedef vector <int> VI;
typedef vector <VI> VVI;
typedef set<PII> SPII;

int w, h;
const int inf = 1<<24;
const int odx[6] = { 0, 1, 1, 1, 0, -1 };
const int ody[6] = { -1, -1, 0, 1, 1, 0 };
const int edx[6] = { -1, 0, 1, 0, -1, -1 };
const int edy[6] = { -1, -1, 0, 1, 1, 0 };

int bfs( VVI& M, int X, int Y ) {
    SPII V;
    Queue Q;
    Node start( X, Y );
    Q.push( start );
    M[Y][X] = 0;
    while ( !Q.empty() ) {
        Node node = Q.front();
        Q.pop();

        int x = node.first;
        int y = node.second;
        if ( V.find( node ) == V.end() ) {
            V.insert( node );
        }

        for ( int i = 0; i < 6; i++ ) {
            int nx = x + ( y%2==0 ? edx[i] : odx[i] );
            int ny = y + ( y%2==0 ? edy[i] : ody[i] );
            if ( nx < 0 || nx >= w || ny < 0 || ny >= h ) continue;
            if ( M[y][x] + 1 >= M[ny][nx] ) continue;
            M[ny][nx] = M[y][x] + 1;
            Node nnode( nx, ny );
            Q.push( nnode );
        }
    }
    return V.size();
}

int main() {
    while ( cin >> w >> h ) {
        VVI M( h+1, VI( w+1, inf ) );

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

        int answer = 0;
        VVI backup = M;
        int t;
        cin >> t;
        for ( int i = 0; i < t; i++ ) {
            M = backup;
            int x, y;
            cin >> x >> y;
            x--;
            y--;
            answer = max( answer, bfs( M, x, y ) );
        }

        cout << answer << endl;
    }
    return 0;
}