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++: #define DEBUG_ON
#define CONDITION true
using namespace std;/*{{{*/

#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <sys/time.h>
#include <vector>

#define INF (1e9)
static const double PI = acos(-1.0);
static const double EPS = 1e-10;

typedef long long int LL;
typedef unsigned long long int ULL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<double> VD;
typedef vector<VD> VVD;
typedef vector<bool> VB;
typedef vector<VB> VVB;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<string> VS;
typedef vector<VS> VVS;
typedef pair<int, int> PII;

#define FOR(i, b, e) for (typeof(e) i = (b); i != (e); i < (e)? ++i : --i)
#define REP(i, n) FOR(i, 0, n)

#define IFC(c) if(c) continue;
#define IFB(c) if(c) break;
#define IFR(c, r) if(c) return r;

#define OPOVER(_op, _type) inline bool operator _op (const _type &t) const

#define arrsz(a) ( sizeof(a) / sizeof(a[0]) )

#define F first
#define S second
#define MP(a, b) make_pair(a, b)

#define SZ(a) ((LL)a.size())
#define PB(e) push_back(e)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())

#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EACH(c,it) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define EXIST(s,e) ((s).find(e)!=(s).end())

#define BIT(n) (assert(n < 64), (1ULL << (n)))
#define BITOF(n, m) (assert(m < 64), ((ULL)(n) >> (m) & 1))

#define RANGE(a, b, c) ((a) <= (b) && (b) <= (c))

#define PQ priority_queue
#define SC static_cast

#ifdef DEBUG_ON
	#define dprt(fmt, ...) if (CONDITION) fprintf(stderr, fmt, ##__VA_ARGS__)
	#define darr(a) if (CONDITION) copy( (a), (a) + arrsz(a), ostream_iterator<int>(cerr, " ") ); cerr << endl
	#define darr_range(a, f, t) if (CONDITION) copy( (a) + (f), (a) + (t), ostream_iterator<int>(cerr, " ") ); cerr << endl
	#define dvec(v) if (CONDITION) copy( ALL(v), ostream_iterator<int>(cerr, " ") ); cerr << endl
	#define darr2(a, n, m) if (CONDITION) FOR(i, 0, (n)){ darr_range( (a)[i], 0, (m) ); }
	#define dvec2(v) if (CONDITION) FOR(i, 0, SZ(v)){ dvec( (v)[i] ); }
	#define WAIT() if (CONDITION) { string _wait_; cerr << "(hit return to continue)" << endl; getline(cin, _wait_); }
	#define dump(x) if (CONDITION) cerr << " [L" << __LINE__ << "] " << #x << " = " << (x) << endl;
	#define dumpf() if (CONDITION) cerr << __PRETTY_FUNCTION__ << endl;
	#define dumpv(x) if (CONDITION) cerr << " [L:" << __LINE__ << "] " << #x << " = "; REP(q, (x).size()) cerr << (x)[q] << " "; cerr << endl;
	#define where() if (CONDITION) cerr << __FILE__ << ": " << __PRETTY_FUNCTION__ << " [L: " << __LINE__ << "]" << endl;
	#define show_bits(b, s) if(CONDITION) { REP(i, s) { cerr << BITOF(b, s-1-i); if(i%4 == 3) cerr << ' '; } cerr << endl; }
#else
	#define cerr if(0) cerr
	#define dprt(fmt, ...)
	#define darr(a)
	#define darr_range(a, f, t)
	#define dvec(v)
	#define darr2(a, n, m)
	#define dvec2(v)
	#define WAIT()
	#define dump(x)
	#define dumpf()
	#define dumpv(x)
	#define where()
	#define show_bits(b, s)
#endif

/* Inline functions */
inline int onbits_count(ULL b) { int c = 0; while(b != 0) { c += (b & 1); b >>= 1; } return c; }
inline int bits_count(ULL b) { int c = 0; while(b != 0) { ++c; b >>= 1; } return c; }
inline int toInt(string s) { int v; istringstream sin(s);sin>>v;return v; }
template<class T> inline string toString(T x) { ostringstream sout;sout<<x;return sout.str(); }
inline double now(){ struct timeval tv; gettimeofday(&tv, NULL); return (static_cast<double>(tv.tv_sec) + static_cast<double>(tv.tv_usec) * 1e-6); }
inline VS split(string s, char delimiter) { VS v; string t; REP(i, s.length()) { if(s[i] == delimiter) v.PB(t), t = ""; else t += s[i]; } v.PB(t); return v; }

/* Tweaks */
template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& d) {return s << "(" << d.first << ", " << d.second << ")";}

/* Frequent stuffs */
// int n_dir = 4;
// int dx[] = {0, 1, 0, -1}, dy[] = {-1, 0, 1, 0}; [> CSS order <]
// enum direction {
	// UP, RIGHT, DOWN, LEFT
// };
// int n_dir = 8;
// int dx[] = {0, 1, 1, 1, 0, -1, -1, -1}, dy[] = {-1, -1, 0, 1, 1, 1, 0, -1};
// enum direction {
	// UP, UPRIGHT, RIGHT, DOWNRIGHT, DOWN, DOWNLEFT, LEFT, UPLEFT
// }
// #define FORDIR(d) REP (d, n_dir)

typedef complex<int> P;
#define Y real()
#define X imag()

/*}}}*/

P dd[8] = { P(-1, 0), P(0, 1), P(1, 0), P(0, -1), P(-1, 1), P(1, 1), P(1, -1), P(-1, -1) };

int main()
{
	queue<P> q;
	VVI field(51, VI(51));
	int w, h;
	while (cin >> w >> h, w | h) {
		REP (i, h) {
			REP (j, w) {
				cin >> field[i][j];
			}
		}
		int ans = 0;
		REP (i, h) {
			REP (j, w) {
				if (field[i][j]) {
					++ans;
					q.push(P(i, j));
					while (!q.empty()) {
						P cpos = q.front(); q.pop();
						field[cpos.Y][cpos.X] = false;
						REP (d, 8) {
							P npos = cpos + dd[d];
							if (0 <= npos.Y && npos.Y < h && 0 <= npos.X && npos.X < w) {
								if (field[npos.Y][npos.X]) {
									q.push(npos);
								}
							}
						}
					}
				}
			}
		}
		cout << ans << endl;
	}
}

// vim: foldmethod=marker

C++: #include<iostream>

using namespace std;

int w, h;
int m[50][50];
void paint(int x, int y) {
	if (x < 0 || x >= w || y < 0 || y >= h) return;
	if (m[y][x] == 0) return;
	m[y][x] = 0;
	for (int dx = -1; dx <= 1; ++dx) for (int dy = -1; dy <= 1; ++dy) {
		paint(x + dx, y + dy);
	}
}
int main() {
	while (cin >> w >> h, w || h) {
		for (int y = 0; y < h; ++y) {
			for (int x = 0; x < w; ++x) {
				cin >> m[y][x];
			}
		}
		int ans = 0;
		for (int y = 0; y < h; ++y) {
			for (int x = 0; x < w; ++x) {
				if (m[y][x]) {
					paint(x, y);
					++ans;
				}
			}
		}
		cout << ans << endl;
	}
}

C++: #include <iostream>
using namespace std;

#define rep(i, a) for (int i = 0; i < a; i++)
#define reps(i, a, b) for (int i = a; i < b; i++)

int W, H;
bool m[52][52];

void reset()
{
	rep(i, 52) rep(j, 52) m[i][j] = false;	
}

void saiki(int r, int c)
{
	if (!m[r][c]) return;
	m[r][c] = false;
	int dr[] = {-1, -1, -1,  0,  0,  1,  1,  1};
	int dc[] = {-1,  0,  1, -1,  1, -1,  0,  1};
	rep(i, 8) saiki(r+dr[i], c+dc[i]);
}


int main(void){
	cin >> W >> H;
	while (H != 0) {
		reset();
		rep(i, H) rep(j, W) {
			int t;
			cin >> t;
			m[i+1][j+1] = t == 1;
		}
		int res = 0;
		rep(i, H) rep(j, W) {
			if (m[i+1][j+1]) {
				res++;
				saiki(i+1, j+1);
			}
		}
		cout << res << endl;
		cin >> W >> H;
	}
}