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 <iostream>
#include <vector>
#include <list>
#include <set>
#include <string>
#include <cmath>
#include <algorithm>
#include <map>

using namespace std;
using ll=long long;
using vi=vector<int>;
using vll=vector<ll>;
using pii=pair<int,int>;
using vs=vector<string>;
using vvi=vector<vi>;
using vpii=vector<pii>;
using si=set<int>;

#define REP(i,a) for(int i=0;i<a;i++)
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define rREP(i,a) for(int i=(a)-1;i>=0;i--)
#define rFOR(i,a,b) for(int i=(a)-1;i>=(b);i--)
#define out(S) cout<<(S)<<endl;
#define beginend(v) (v).begin(),(v).end()
#define IfOut(condition,text) if(condition){out(text);return 0;}
#define IfOutElse(condition,if_text,else_text) if(condition){out(if_text);return 0;}else{out(else_text);return 0;}
#define mod(s) ((s)%(ll)(1e9+7))
ll modpow(ll i, ll j) { ll tmp = 1; while (j) { if (j % 2)tmp = mod(tmp*i); i = mod(i*i); j /= 2; }return tmp; }
#define divmod(a,b) (mod(a*modpow((ll)b,(ll)(1e9+5))))
#define pb(i) push_back(i)
#define fst first
#define snd second
#define Foreach(item,collection) for(auto item:collection)
#define INF (int)1e10
#define removeAll(vec,deleg) auto itr=remove_if(beginend(vec),deleg);vec.erase(itr,vec.end());
void removeAt(string& s, int index) { s.erase(index, 1); }
template<typename T> void removeAt(vector<T>& v, int index) { v.erase(v.begin() + index); }
ll manhattanDistance(ll x1, ll y1, ll x2, ll y2) { return (abs(x2 - x1) + abs(y2 - y1)); }
vector<ll> sieveOfEratosthenes(int max) {ll prime;double sqrtmax = sqrt(max);vector<ll> primeVec, searchVec;FOR(i, 2, max + 1) searchVec.push_back(i);do{prime = searchVec[0];primeVec.push_back(prime);auto itr = remove_if(beginend(searchVec), [=](ll x)->bool {return x%prime == 0; });searchVec.erase(itr, searchVec.end());} while (prime < sqrtmax);primeVec.reserve(primeVec.size() + searchVec.size());primeVec.insert(primeVec.end(), beginend(searchVec));return primeVec;}
ll sum(vi v) {ll sum=0;Foreach(i,v){sum+=i;}return sum;}
#define ShowAll(v) Foreach(i,v) out(i);
bool isInnerIndex(ll x,ll y,ll mx,ll my){ return (x>=0&&x<mx&&y>=0&&y<my); }

int x,y;
vvi box;
int dx[]{0,1,0,-1,1,1,-1,-1};
int dy[]{1,0,-1,0,-1,1,-1,1};
ll s=0;
void dfs(int px,int py){
    out("--------------");
    REP(i,8){
        int nx=px+dx[i];
        int ny=py+dy[i];
        if(isInnerIndex(nx,ny,x,y)&&box[ny][nx]==1){
            dfs(nx,ny);
        }
    }
    return;
}

int main(){
    vi ans;
    while (cin>>x>>y,(x||y))
    {
        box.clear();
        box.resize(y);
        REP(i,y) REP(n,x) {
            int c;
            cin>>c;
            box[i].pb(c);
        }
        ll s=0;
        REP(i,y)REP(n,x){
            if(box[i][n]==1) {dfs(n,i);s++;}
        }
        ans.pb(s);
    }
    
    ShowAll(ans);
    return 0;
}

C++: #include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll MOD = 1000000007;

#define vec                vector<int>
#define vecll              vector<ll>
#define vecd               vector<double>
#define vecst              vector<string>
#define vecb               vector<bool>
#define vec2(var, n, m)    vector<vector<int>> var(n, vector<int>(m, 0))
#define vecll2(var, n, m)  vector<vector<ll>> var(n, vector<ll>(m, 0))

#define rep(i,n)         for(ll i=(ll)0; i<(ll)n; i++)
#define REP(i,m,n)       for(ll i=(ll)m; i<(ll)n; i++)
#define arr(var, n)      vec var(n); rep(i,n){cin >> var[i];}
#define arrll(var, n)    vecll var(n); rep(i,n){cin >> var[i];}
#define arrst(var, n)    vecst var(n); rep(i,n){cin >> var[i];}
#define all(var)         (var).begin(), (var).end()
#define sortall(var)     sort(all(var))
#define uniqueall(v)     v.erase(unique(v.begin(), v.end()), v.end());
#define f_sum(var)       accumulate(all(var), 0)
#define f_sumll(var)     accumulate(all(var), 0LL)
#define chmin(v1, v2)    v1 = min(v1, v2)
#define chmax(v1, v2)    v1 = max(v1, v2)
#define pb(var)          push_back(var)
#define prt(var)         cout << (var) << "\n"
#define prtd(n, var)     cout << fixed << setprecision(n) << var << "\n"
#define prtfill(n, var)  cout << setw(n) << setfill('0') << var;
#define prt2(v1, v2)     cout << v1 << " " << v2 << "\n"
#define prt3(v1, v2, v3) cout << v1 << " " << v2 << " " << v3 << "\n"
#define prtall(v)        rep(i,v.size()){cout<<v[i]<<(i!=v.size()-1?" ":"\n");}
void prtok(bool ok){prt(ok ? "yes" : "no");}
//----------------------------------------------------------------
bool ch[51][51];
int h, w;

void dfs(vector<vector<bool>> mp, int i, int j){
  //prt3("--->", i, j);
  ch[i][j] = true;
  bool up=true, down=true, left=true, right=true;

  if(i==0) up=false;
  if(i==h-1) down=false;
  if(j==0) left=false;
  if(j==w-1) right=false;

  if(up && left){if(mp[i-1][j-1] && !ch[i-1][j-1]) dfs(mp, i-1, j-1);}
  if(up) {if(mp[i-1][j] && !ch[i-1][j]) dfs(mp, i-1, j);}
  if(up && right) {if(mp[i-1][j+1] && !ch[i-1][j+1]) dfs(mp, i-1, j+1);}
  if(left) {if(mp[i][j-1] && !ch[i][j-1]) dfs(mp, i, j-1);}
  if(right) {if(mp[i][j+1] && !ch[i][j+1]) dfs(mp, i, j+1);}
  if(down && left) {if(mp[i+1][j-1] && !ch[i+1][j-1]) dfs(mp, i+1, j-1);}
  if(down) {if(mp[i+1][j] && !ch[i+1][j]) dfs(mp, i+1, j);}
  if(down && right) {if(mp[i+1][j+1] && !ch[i+1][j+1]) dfs(mp, i+1, j+1);}
}

int main(void) {
  while(1){
    rep(i,51){
      rep(j,51){
        ch[i][j]=false;
      }
    }
    cin >> w >> h;

    if(w==0 && h==0){break;}
    vector<vector<bool>> mp(h, vector<bool>(w, false));
    rep(i,h){
      rep(j,w){
        int tmp;
        cin >> tmp;
        mp[i][j] = (tmp>0 ? true : false);
      }
    }

    int ans=0;
    rep(i,h){
      rep(j,w){
        if(!ch[i][j] && mp[i][j]){
          ans++;
          dfs(mp, i, j);
        }
      }
    }
    prt(ans);
  }
}

C++: #include <iostream>

int w,h;
int c[50][50];

void dfs(int x,int y){
    c[x][y] = 0;
    for(int dx=-1;dx<=1;dx++){
        for(int dy=-1;dy<=1;dy++){
            int nx = x+dx,ny= y+dy;
            if(0<=nx&&nx<h&&0<=ny&&ny<w&&c[nx][ny] == 1){
                dfs(nx,ny);
            }
        }
    }
    return;
}

int main(){
    while(1){
        std::cin >> w >> h;
        if(w==0&&h==0) break;
        for(int j=0;j<h;j++){
            for(int i=0;i<w;i++){
                std::cin >> c[j][i];
            }
        }
        int num = 0;
        for(int i=0;i<w;i++){
            for(int j=0;j<h;j++){
                if(c[j][i] == 1){
                    dfs(j,i);
                    num++;
                }
            }
        }
        std::cout << num << std::endl;
    }
}