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++: #include <bits/stdc++.h>
#define FOR(i, m, n) for (int i = m; i < (n); i++)
#define RFOR(i, m, n) for (int i = (m - 1); i >= 0; i--)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, n, 0)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
#define print(ele) cout << ele << endl
#define print10(ele) cout << fixed << setprecision(10) << ele << endl

using namespace std;
typedef long long ll;
const int mod = 1e9 + 7;
const ll INF = 1000000000000000000LL;

struct mint {
  ll x;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod - a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint& operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

mint factorial(ll n) {
  mint answer = 1;
  while (n > 1) {
    answer *= n;
    n--;
  }
  return answer;
}

mint combination(ll n, ll r) {
  return factorial(n) / (factorial(r) * factorial(n - r));
}

mint permutation(ll n, ll r) { return factorial(n) / factorial(n - r); }

// setprecision(8) 桁数指定
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

template <typename T>
void remove(std::vector<T>& vector, unsigned int index) {
  vector.erase(vector.begin() + index);
}

map<ll, ll> prime_factor(ll n) {
  map<ll, ll> ret;
  for (ll i = 2; i * i <= n; i++) {
    while (n % i == 0) {
      ret[i]++;
      n /= i;
    }
  }
  if (n != 1) ret[n] = 1;
  return ret;
}
// for (auto p : prime_factor(n)) {
//	while (p.second--) {
//		cout << p.first << endl;
//	}
//}

vector<ll> divisor(ll n) {
  vector<ll> ret;
  for (ll i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i * i != n) ret.push_back(n / i);
    }
  }
  sort(begin(ret), end(ret));
  return (ret);
}

bool compare_by_b(pair<ll, ll> a, pair<ll, ll> b) {
  if (a.second != b.second) {
    return a.second < b.second;
  } else {
    return a.first < b.first;
  }
}

vector<ll> Eratosthenes(const ll N) {
  bool is_prime[1000000 + 1];
  vector<ll> P;
  for (ll i = 0; i <= N; i++) {
    is_prime[i] = true;
  }
  for (ll i = 2; i <= N; i++) {
    if (is_prime[i]) {
      for (ll j = 2 * i; j <= N; j += i) {
        is_prime[j] = false;
      }
      P.emplace_back(i);
    }
  }
  return P;
}

typedef vector<int> ivec;
typedef vector<string> svec;
typedef vector<ll> lvec;

int H, W;
vector<vector<int>> field;

void dfs(int x, int y) {
  field[x][y] = 0;

  FOR(dx, -1, 2) FOR(dy, -1, 2) {
    int nx = x + dx, ny = y + dy;

    if (nx < 0 || nx >= H || ny < 0 || ny >= W) continue;
    if (field[nx][ny] == 0) continue;

    dfs(nx, ny);
  }
}

int main() {
  while (1) {
    cin >> W >> H;
    if (H == 0 && W == 0) break;

    field.assign(H, ivec(W, 0));

    REP(x, H) REP(y, W) cin >> field[x][y];

    int count = 0;
    REP(x, H) REP(y, W) {
      if (field[x][y] == 0) continue;
      dfs(x, y);
      count++;
    }

    print(count);
  }
  return 0;
}

C++: //
// Created by elegant-belltree on 15/06/03.
//

#include <iostream>
#include <set>

using namespace std;

int main(){
    int w,h;
    int c[50][50];

    while (cin>>w>>h && (w>0 || h>0)) {
        int label=2;
        set<int> labels;

        for (int n = 0; n < 2; ++n) {
            for (int i = 0; i < h; ++i) {
                for (int j = 0; j < w; ++j) {
                    if(n==0) {
                        cin >> c[j][i];
                    }
                    if (0<c[j][i]) {
                        for (int k = -1; k < n+1; ++k) {
                            for (int l = -1; (n!=0 || k!=0 || l!=0) && l < 3 && j + l < w; ++l) {
                                if (-1 < i + k && -1 < j + l && 0 < c[j + l][i + k] && (c[j][i] == 1 || c[j + l][i + k] < c[j][i])) {
                                    if(n==1){
                                        labels.erase(c[j][i]);
                                    }
                                    c[j][i] = c[j + l][i + k];
                                }
                            }
                        }
                        if (c[j][i] == 1) {
                            c[j][i] = label++;
                            labels.insert(c[j][i]);
                        }
                    }
                }
            }
        }
        /*for (int m = 0; m < h; ++m) {
            for (int i = 0; i < w; ++i) {
                cout<<c[i][m]<<" ";
            }
            cout<<endl;
        }*/
        cout<<labels.size()<<endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define i_7 (ll)(1E9+7)
#define i_5 (ll)(1E9+5)
ll mod(ll a){
    ll c=a%i_7;
    if(c>=0)return c;
    else return c+i_7;
}
typedef pair<int,int> i_i;
typedef pair<ll,ll> l_l;
ll inf=(ll)1E12;//10^12
#define rep(i,l,r) for(ll i=l;i<=r;i++)
#define pb push_back
ll max(ll a,ll b){if(a<b)return b;else return a;}
ll min(ll a,ll b){if(a>b)return b;else return a;}
const double EPS=1E-8;
////////////////////////////////////////

int w,h;
bool m[55][55];

void dfs(int k,int l){
    
    rep(i,-1,1)rep(j,-1,1){
        int x=k+i;int y=l+j;
        if(0<=x&&x<=h-1&&0<=y&&y<=w-1&&m[x][y]){
            
            m[x][y]=false;
            dfs(x,y);
        }
    }
}


int main() {
    ios::sync_with_stdio(false);cin.tie(0);
    
    while(cin>>w>>h){
        if(w==0)break;
        rep(i,0,h-1)rep(j,0,w-1)cin>>m[i][j];
        int ans=0;
        rep(i,0,h-1)rep(j,0,w-1){
            if(m[i][j]){
                ans++;
                m[i][j]=false;
                dfs(i,j);
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}