Go: package main

import (
	"bufio"
	"fmt"
	"io"
	"math"
	"os"
	"strconv"
)

var (
	readString func() string
	readBytes  func() []byte
	stdout     *bufio.Writer
)

func init() {
	readString, readBytes = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func newReadString(ior io.Reader) (func() string, func() []byte) {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), math.MaxInt32)
	r.Split(bufio.ScanWords)

	f1 := func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
	f2 := func() []byte {
		return []byte(f1())
	}
	return f1, f2
}

func readInt() int {
	return int(readInt64())
}

func readInt64() int64 {
	i, err := strconv.ParseInt(readString(), 10, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func readFloat64() float64 {
	f, err := strconv.ParseFloat(readString(), 64)
	if err != nil {
		panic(err.Error())
	}
	return f
}

func printf(f string, args ...interface{}) (int, error) {
	return fmt.Fprintf(stdout, f, args...)
}

func println(args ...interface{}) (int, error) {
	return fmt.Fprintln(stdout, args...)
}

func eprintln(args ...interface{}) (int, error) {
	return fmt.Fprintln(os.Stderr, args...)
}

func eprintf(f string, args ...interface{}) (int, error) {
	return fmt.Fprintf(os.Stderr, f, args...)
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func min64(a, b int64) int64 {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

func max64(a, b int64) int64 {
	if a < b {
		return b
	}
	return a
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func abs64(a int64) int64 {
	if a < 0 {
		return -a
	}
	return a
}

func gcd(a, b int) int {
	if b == 0 {
		return a
	}
	return gcd(b, a%b)
}

func gcd64(a, b int64) int64 {
	if b == 0 {
		return a
	}
	return gcd64(b, a%b)
}

// readString() string
// readInt() int
// readInt64() int64
// readFloat64() float64

// -----------------------------------------------------------------------------

func main() {
	defer stdout.Flush()

	for {
		ans, ok := solve()
		if !ok {
			break
		}
		println(ans)
	}

}

func solve() (int, bool) {
	w := readInt()
	h := readInt()
	if w == 0 && h == 0 {
		return 0, false
	}

	c := make([][]int, h+2)
	c[0] = make([]int, w+2)
	c[h+1] = make([]int, w+2)
	for i := 1; i-1 < h; i++ {
		c[i] = make([]int, w+2)
		for j := 1; j-1 < w; j++ {
			c[i][j] = readInt()
		}
	}

	var ans int
	for i := 1; i-1 < h; i++ {
		for j := 1; j-1 < w; j++ {
			if 0 < c[i][j] {
				ans++
				dfs(c, i, j)
			}
		}
	}
	return ans, true
}

func dfs(c [][]int, y, x int) {
	c[y][x] = 0
	dx := []int{-1, 0, 1, -1, 1, -1, 0, 1}
	dy := []int{-1, -1, -1, 0, 0, 1, 1, 1}
	for i := range dx {
		nx := x + dx[i]
		ny := y + dy[i]
		if 0 < c[ny][nx] {
			dfs(c, ny, nx)
		}
	}
}

// -----------------------------------------------------------------------------

C++: #include <bits/stdc++.h>
using namespace std;

struct UnionFind {
    vector<int> data;
    int sz;
    UnionFind(int sz) : data(sz, -1), sz(sz) { }
    bool unionSet(int x, int y) {
        if ((x = root(x)) == (y = root(y))) return false;
        if (data[x] > data[y]) swap(x, y);
        data[x] += data[y]; data[y] = x; sz--;
        return true;
    }
    bool findSet(int x, int y) { return root(x) == root(y); }
    int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
    int size(int x) { return -data[root(x)]; }
    int size() { return sz; }
};

int X[8] = {1, 1, 0, -1, -1, -1, 0, 1};
int Y[8] = {0, 1, 1, 1, 0, -1, -1, -1};

int main(){
    while(true){
    int H, W;
    cin >> W >> H;
    if(H == 0 && W == 0)break;
    vector<vector<bool>> F(H, vector<bool>(W));
    UnionFind uf(H * W);
    for(int i = 0; i < H; i++){
        for(int j = 0; j < W; j++){
            int a;cin >> a;
            if(a == 0)F[i][j] = false;
            else F[i][j] = true;
        }
    }
    
    for(int i = 0; i < H; i++){
        for(int j = 0; j < W; j++){
            if(F[i][j]){
                for(int X = -1; X <= 1; X++){
                    for(int Y = -1; Y <= 1; Y++){
                    int x = j + X;
                    int y = i + Y;
                    if(x < 0 || W <= x || y < 0 || H <= y)continue;
                    else if(F[y][x])uf.unionSet(i * W + j, y * W + x);
                    }
                }
            }
        }
    }
    /*
    set<int> R;
    for(int i = 0; i < H * W; i++)R.insert(uf.root(i));
    //cout << uf.root(2) << endl;
    int ans = R.size();
    //cout << ans << endl;
    */
    int ans = uf.size();
    for(int i = 0; i < H; i++){
        for(int j = 0; j < W; j++){
            if(F[i][j])continue;
            else ans--;
        }
    }
    
    cout << ans << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include<stack>
#include<queue>
#include<map>
#include<set>

using namespace std;

typedef long long ll;
typedef vector<int> VI;

#define FOR(i,n) for(int (i)=0;(i)<(n);(i)++)
#define FOR1(i,n) for(int (i)=1;(i)<(n);(i)++)
#define eFOR(i,n) for(int (i)=0;(i)<=(n);(i)++)
#define eFOR1(i,n) for(int (i)=1;(i)<=(n);(i)++)
#define SORT(i) sort((i).begin(),(i).end())
constexpr auto INF = 1000000000;
constexpr auto LLINF = 9223372036854775807;
constexpr auto mod = 1000000007;

int w, h, c[50][50];
int dx[8] = { -1,0,1,-1,1,-1,0,1 }, dy[8] = { -1,-1,-1,0,0,1,1,1 };
void search(int x, int y) {
	if (x >= 0 && x < w && y >= 0 && y < h) {
		if (c[y][x] == 1) {
			c[y][x] = 0;
			FOR(k, 8)search(x + dx[k], y + dy[k]);
		}
	}
}

int main() {
	while (1) {
		cin >> w >> h;
		if (w == 0 && h == 0)break;
		FOR(i, h)FOR(j, w)cin >> c[i][j];
		int cnt = 0;
		FOR(i, h)FOR(j, w)if (c[i][j] == 1) {
			search(j, i);
			cnt++;
		}
		cout << cnt << endl;
	}
	

	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<stack>
#include<queue>
#include<string.h>
#include<string>
#include<functional>
#include<set>
using namespace std;

#define INF 1<<21
#define DIV 1000000007
#define MAX 250000

int table[51][51];
int W, H;

void dfs(int x, int y) {
  table[y][x] = 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 < W && 0 <= ny&&ny < H&&table[ny][nx] == 1)dfs(nx, ny);
	}
  }
  return;
}

int main(){
  while (cin >> W >> H, W || H) {
	int ans = 0;
	memset(table, 0, sizeof(table));
	int t;
	for (int y = 0; y < H; y++) {
	  for (int x = 0; x < W; x++) {
		cin >> table[y][x];
	  }
	}

	for (int y = 0; y < H; y++) {
	  for (int x = 0; x < W; x++) {
		if (table[y][x] == 1) {
		  dfs(x, y);
		  ans++;
		}
	  }
	}
	cout << ans << endl;
  }

}