Go: ///
// File:  1160.go
// Author: ymiyamoto
//
// Created on Sun Mar  4 20:45:57 2018
//
package main

import (
	"fmt"
)

var w, h int
var graph [][]string

func dfs(visited [][]bool, x, y int) {
	visited[x][y] = true

	for i := -1; i <= 1; i++ {
		for j := -1; j <= 1; j++ {
			dx := x + i
			dy := y + j
			if 0 <= dx && dx < h && 0 <= dy && dy < w && graph[dx][dy] == "1" && !visited[dx][dy] {
				dfs(visited, dx, dy)
			}
		}
	}
}

func main() {
	for {
		fmt.Scan(&w, &h)
		if w == 0 && h == 0 {
			break
		}

		graph = make([][]string, h)
		for i := range graph {
			graph[i] = make([]string, w)
		}

		for i := 0; i < h; i++ {
			for j := 0; j < w; j++ {
				var s string
				fmt.Scan(&s)
				graph[i][j] = s
			}
		}

		visited := make([][]bool, h)
		for i := range visited {
			visited[i] = make([]bool, w)
		}

		count := 0
		for i := range graph {
			for j := range graph[i] {
				if graph[i][j] == "1" && !visited[i][j] {
					dfs(visited, i, j)
					count++
				}
			}
		}

		fmt.Println(count)
	}
}

C++: /**Function Template**/
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> pint;
const int MAX = 510000;
const int MOD = 1000000007;
#define rep(i, n) for(ll i = ll(0); i < ll(n); i++)
#define Rep(i, n) for(ll i = ll(1); i < ll(n); i++)
#define ALL(a)  (a).begin(),(a).end()
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define PI 3.14159265358979323846
#define ifYN(x) cout<<(x?"Yes":"No")<<"\n" 
ll fac[MAX], finv[MAX], inv[MAX];


template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

bool palindrome(string s){
  bool flag=true;
  rep(i,(ll)s.size()) if(s[i]!=s[s.size()-1-i]) flag=false;
  return flag;
}

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }

}
ll Len(ll n) {
  ll s=0;
  while(n!=0) s++, n/=10;
  return s;
}


ll Sint(ll n) {
  ll ans=0;
  while(n!=0) ans+=n%10,n/=10;
  return ans;
}

ll Svec(vector<ll> v){
  ll n=0;
  rep(i,(ll)v.size()) n+=v[i];
  return n;
}


ll GCD(ll a,ll b) {
  return b ? GCD(b,a%b) : a;
}


ll LCM(ll a,ll b){
  return a/GCD(a,b)*b;
}


ll Factorial(ll n){
  ll m=1;
  while(n>=1) m*=n,n--;
  return m;
}

void runlength(string s,vector<pair<char,ll>> &p){
  ll x=1;
  if(s.size()==1){
    p.push_back(pair<char,ll>(s[0],1));
  }
  rep(i,(ll)s.size()-1){
    if(s[i]==s[i+1]){
      x++;
      if(i==(ll)s.size()-2){
        p.push_back(pair<char,ll>(s[i],x));
      }
    }else{
      p.push_back(pair<char,ll>(s[i],x));
      x=1;
      if(i==(ll)s.size()-2){
        p.push_back(pair<char,ll>(s[s.size()-1],x));
      }
    }
  }
}

ll COM(ll n,ll k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

ll modpow(ll a, ll n, ll mod) {
    ll res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

string Toupper(string s){
  string ans="";
  rep(i,s.size()){
    if('a'<=s[i] && s[i]<='z') ans+=(char)s[i]-32;
    else ans+=s[i];
  }
  return ans;
}
string Tolower(string s){
  string ans="";
  rep(i,s.size()){
    if('A'<=s[i] && s[i]<='Z') ans+=(char)s[i]+32;
    else ans+=s[i];
  }
  return ans;
}

void dis(vector<ll> v){ rep(i,v.size()) cout<<v[i]<<endl; }

void dis2(vector<vector<ll>> v){
  rep(i,v.size()){
    rep(j,v[0].size()) cout<<v[i][j]<<' ';
    cout<<endl;
  }
}

const int MAX_N=100010;
vector<bool> sieve_of_eratosthenes(){
  vector<bool> isPrime(MAX_N+1,true);
  /* isPrime[1]=false; */
  for(int i=2;i<=MAX_N;i++){
    if(isPrime[i]){
      for(int j=2*i;j<=MAX_N;j+=i){
        isPrime[j]=false;
      }
    }
  }
  return isPrime;
}

vector<pint> prime_factorize(ll n){
  vector<pint> ans;
  for(ll p=2;p<=sqrt(n);p++){
    if(n%p!=0) continue;
    ll cnt=0;
    while(n%p==0){
      n/=p;
      cnt++;
    }
    ans.push_back(make_pair(p,cnt));
  }
  if(n!=1) ans.push_back(make_pair(n,1));
  return ans;
}

/*bool cmp(pint a, pint b) { return a.second < b.second; }*/
ll w,h;
ll ans=0;
vector<vector<ll>> v(60,vector<ll>(60));
ll dx[8]={-1,0,1,-1,1,-1,0,1};
ll dy[8]={-1,-1,-1,0,0,1,1,1};
vector<vector<bool>> reached(60,vector<bool>(60,false));

void dfs(ll x,ll y){
  if(x<0 || w<=x || y<0 || h<=y) return;
  if(reached[y][x]) return;
  if(v[y][x]==0) return;
  reached[y][x]=true;
  rep(i,8) dfs(x+dx[i],y+dy[i]);
}
/*↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓*/
int main() {
  IOS;
  while(1){
    cin>>w>>h;
    ans=0;
    if(w==0 && h==0) break;
    rep(i,h) rep(j,w) cin>>v[i][j];
    rep(i,h) rep(j,w) reached[i][j]=false;
    rep(i,h) rep(j,w) if(!reached[i][j] && v[i][j]==1) dfs(j,i),ans++;
    cout<<ans<<endl;
  }
}

C++: #include <iostream>
#include <stdio.h>
#include <algorithm>
#include <math.h>
#include <vector>
#include <string>
#include <sstream>
#include <numeric>
#include <set>
#include <map>

#define rep(i, j) for(int i = 0; i < j; i++)
#define all(i) i.begin(), i.end()
#define ll long long
#define bl bool
#define nn printf("\n");
#define mod 1000000007

using namespace std;

int w, h, cnt = 0;

void srch(int x, int y, vector<vector<int>> &inp, vector < vector <bool>> &hit)
{
	if (x < 0 || w <= x || y < 0 || h <= y || inp[y][x] == 0) { return; }
	if (hit[y][x]) return;
	hit[y][x] = true;
	cnt += 1;
	srch(x + 1, y, inp, hit);
	srch(x - 1, y, inp, hit);
	srch(x, y + 1, inp, hit);
	srch(x, y - 1, inp, hit);
	srch(x + 1, y + 1, inp, hit);
	srch(x + 1, y - 1, inp, hit);
	srch(x - 1, y + 1, inp, hit);
	srch(x - 1, y - 1, inp, hit);
}
int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	while (cin >> w >> h && w != 0 && h != 0)
	{
		vector<vector<int>> inp(h, vector<int>(w, 0));
		vector<vector<bool>> hit(h, vector<bool>(w, false));
		int ans = 0;
		rep(y, h) rep(x, w){ cin >> inp[y][x]; }
		rep(y, h) rep(x, w)
		{
			srch(x, y, inp, hit);
			if (cnt > 0) { ans += 1; }
			cnt = 0;
		}
		printf("%d\n", ans);
	}

	return 0;
}

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

using namespace std;

int w,h,res;
vector<vector<int> > map;
vector<vector<bool> > visited;
int dx[8] = {0,1,0,-1,1,1,-1,-1};
int dy[8] = {1,0,-1,0,1,-1,1,-1};

void bfs(int y,int x){
	if(y >= h || y < 0 || x >= w || x < 0)return;
	if(map[y][x] == 0)return;
	if(visited[y][x])return;
	visited[y][x] = true;
	for(int i=0;i<8;++i){
		bfs(y+dy[i],x+dx[i]);
	}
}

int main(void){
	while(1){
		res = 0;
		cin >> w >> h;
		if(w == 0 && h == 0)break;
		map.resize(h);
		visited.resize(h);
		for(int i=0;i<h;++i){
			map[i].resize(w);
			visited[i].resize(w);
			for(int j=0;j<w;++j){
				visited[i][j] = false;
				cin >> map[i][j];
			}
		}
		for(int i=0;i<h;++i){
			for(int j=0;j<w;++j){
				if(map[i][j] == 1&& visited[i][j] == false){
					bfs(i,j);
					res++;
				}
			}
		}
		cout << res << endl;
	}
}