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;

typedef long long ll;
typedef pair<int, int> duo;

#define TT template<typename T>
TT T    sq(T x){ return x*x; }
TT int  ubnd(vector<T>& v,T x){ return upper_bound(v.begin(), v.end(), x) - v.begin(); }
TT int  lbnd(vector<T>& v,T x){ return lower_bound(v.begin(), v.end(), x) - v.begin(); }
TT void sort(T& v){ sort(v.begin(), v.end()); }
TT void revs(T& v){ reverse(v.begin(), v.end()); }
TT void uniq(T& v){ sort(v); v.erase(unique(v.begin(), v.end()), v.end()); }
TT void show(T& v,char d=' ',char e='\n'){for(int i=0;i<v.size();++i)cout<<v[i]<<((i==v.size()-1)?e:d);}
TT void inpt(vector<T>& v,int n){ v.reserve(n);for(int i=0;i<n;++i){T x; cin>>x; v.push_back(x);} }
TT T    In(T& x){ cin >> x; return x; }

static inline void fast_io(){ ios::sync_with_stdio(0); cin.tie(0); }
static inline int in(){ int x; scanf("%d", &x); return x; }
static inline string instr(){ string x; cin >> x; return x; }
static const int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
static const int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};

struct Solver {
  Solver(int w, int h) : w(w), h(h) { memset(field, 0, sizeof(field)); }
  void input(){
    for (int y = 0; y < h; y++){
      for (int x = 0; x < w; x++){
        field[y][x] = in();
      }
    }
  }
  int solve(){
    int count = 0;
    for (int y = 0; y < h; y++){
      for (int x = 0; x < w; x++){
        if (field[y][x]){
          count++;
          erase(x, y);
        }
      }
    }
    return count;
  }

  void erase(int x, int y){
    if (invalid(x, y)) return;
    if (!field[y][x]) return;
    field[y][x] = 0;
    for (int d = 0; d < 8; d++){
      erase(x + dx[d], y + dy[d]);
    }
  }
  bool invalid(int x, int y){
    return x < 0 || w <= x || y < 0 || h <= y;
  }
  const int w, h;
  int field[64][64];
};

int main()
{
  int w, h;
  while (w = in(), h = in()){
    Solver s(w, h);
    s.input();
    printf("%d\n", s.solve());
  }
  return (0);
}

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

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

void dfs(int y, int x)
{
  int dx[]={1,-1,0,0};
  int dy[]={0,0,1,-1};

  maps[y][x]=0;

  for(int i=0;i < 4;i++){
    for(int j=0;j < 4;j++){
      int xx = x + dx[j];
      int yy = y + dy[i];
      if(maps[yy][xx] == 1 && xx >= 0 && xx < w && yy >= 0 && yy < h) dfs(yy,xx);
    }
  }
}

int main(){
  while(cin >> w >> h && w)
    {
      for(int i=0;i < h;i++){
	for(int j=0;j < w;j++){
	  cin >> maps[i][j];
	}
      }
      int island=0;

      for(int i=0;i < h;i++){
	for(int j=0;j < w;j++){
	  if(maps[i][j] == 1){
	    island++;
	    dfs(i,j);
	  }
	}
      }
      cout << island << endl;
    }
  return 0;
}

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

static const int MAX_H = 50;
static const int MAX_W = 50;

int H, W;
char grid[MAX_H][MAX_W + 1];
bool reached[MAX_H][MAX_W];

#define OCTAS
#ifdef OCTAS
static const int dh[]{-1, -1, -1, 0, 0, +1, +1, +1};
static const int dw[]{-1, 0, +1, -1, +1, -1, 0, +1};
#else
static const int dh[]{-1, 0, 0, +1};
static const int dw[]{0, -1, +1, 0};
#endif

bool dfs(int h, int w) {
  reached[h][w] = true;

  for (int i{}; i < sizeof(dh) / sizeof(int); ++i) {
    int nh = h + dh[i];
    if (nh < 0 || nh >= H)
      continue;
    int nw = w + dw[i];
    if (nw < 0 || nw >= W)
      continue;
    if (grid[nh][nw] == '0' || reached[nh][nw])
      continue;
    if (dfs(nh, nw))
      return true;
  }

  return false;
}

int main() {
  while (true) {
    cin >> W >> H;
    if (W == 0 && H == 0) break;
    for (int h{}; h < H; ++h) {
      for (int w{}; w < W; ++w) {
        cin >> grid[h][w];
      }
    }
    fill_n(reached[0], MAX_H * MAX_W, false);
    int count{};
    for (int h{}; h < H; ++h) {
      for (int w{}; w < W; ++w) {
        if (grid[h][w] == '0' || reached[h][w])
          continue;
        dfs(h, w);
        ++count;
      }
    }
    cout << count << endl;
  }
}