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<iostream>
#include<vector>
#include<stack>
using namespace std;

typedef long long itemType;

struct node
{long long v; struct node *next;};

void visit(stack<long long> stack, long long k, struct node *z, struct node **adj, long long id, long long val[]){
    struct node *t;
    t = new node;
    stack.push(k);
    while(!stack.empty()){
        k = stack.top();
        stack.pop();
        val[k] = ++id;
        for(t = adj[k]; t != z; t = t -> next){
            if(val[t -> v] == 0){
                stack.push(t -> v);
                val[t -> v] = -1;
            }
        }
    }
}

void search(stack<long long>stack, long long V, struct node *z, struct node **adj, long long id, long long val[], long long &comp, vector<vector<bool> > c, long long w){
    long long k;
    for(k = 1; k <= V; k++) val[k] = 0;
    for(k = 1; k <= V; k++){
        if(val[k] == 0){
            if(c[(k-1)/w + 1][((k-1)%w) + 1]) comp++;
            visit(stack, k, z, adj, id, val);
        }
    }
}

int main(){
    long long w, h;
    vector<bool> sub;
    bool c_sub;
    long long i, j;
    for(i = 0; i <= 50; i++){
        sub.push_back(0);
    }
    vector<vector<bool> > c;
    for(i = 0; i <= 50; i++){
        c.push_back(sub);
    }
    long long V;
    struct node *z;
    z = new node;
    z -> next = z;
    struct node *adj[2501];
    struct node *t;
    long long x, y;
    while(1){

        //input
        cin >> w >> h;
        if(w == 0 && h == 0) break;
        for(i = 1; i <= h; i++){
            for(j = 1; j <= w; j++){
                cin >> c_sub;
                c[i][j] = c_sub;
            }
        }

        //adjacency list representation
        V = w * h;
        stack<long long> stack;
        for(i = 1; i <= V; i++){
            adj[i] = z;
        }
        for(j = 1; j <= w; j++){
            for(i = 1; i <= h-1; i++){
                if(c[i][j] & c[i+1][j]){
                    x = (i-1)*w + j;
                    y = i*w + j;
                    t = new node;
                    t -> v = x;
                    t -> next = adj[y];
                    adj[y] = t;
                    t = new node;
                    t -> v = y;
                    t -> next = adj[x];
                    adj[x] = t;
                    
                }
            }
        }
        
        for(i = 1; i <= h; i++){
            for(j = 1; j <= w-1; j++){
                if(c[i][j] & c[i][j+1]){
                    x = (i-1)*w + j;
                    y = (i-1)*w + j+1;
                    t = new node;
                    t -> v = x;
                    t -> next = adj[y];
                    adj[y] = t;
                    t = new node;
                    t -> v = y;
                    t -> next = adj[x];
                    adj[x] = t;
                    
                }
            }
        }
        for(i = 1; i <= h-1; i++){
            for(j = 1; j <= w-1; j++){
                if(c[i][j] & c[i+1][j+1]){
                    x = (i-1)*w + j;
                    y = i*w + j+1;
                    t = new node;
                    t -> v = x;
                    t -> next = adj[y];
                    adj[y] = t;
                    t = new node;
                    t -> v = y;
                    t -> next = adj[x];
                    adj[x] = t;
                    
                }
            }
        }
        for(i = 1; i <= h-1; i++){
            for(j = 1; j <= w-1; j++){
                if(c[i+1][j] & c[i][j+1]){
                    x = i*w + j;
                    y = (i-1)*w + j+1;
                    t = new node;
                    t -> v = x;
                    t -> next = adj[y];
                    adj[y] = t;
                    t = new node;
                    t -> v = y;
                    t -> next = adj[x];
                    adj[x] = t;
                    
                }
            }
        }

        //depth first search
        long long id = 0;
        long long val[V + 1];
        long long comp = 0;
        search(stack, V, z, adj, id, val, comp, c, w);
        cout << comp << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <algorithm>

using namespace std;

int c[50][50];

int dx[8] = {-1,-1,-1, 0, 0, 1, 1, 1};
int dy[8] = {-1, 0, 1,-1, 1,-1, 0, 1};

int ret;

int w,h;

void dfs(int x,int y){
	if(c[x][y] == 0) return;
	c[x][y] = 0;
	for(int i=0;i<8;i++){
		if(x+dx[i] < 0 || x+dx[i] >= w) continue;
		if(y+dy[i] < 0 || y+dy[i] >= h) continue;
		dfs(x+dx[i],y+dy[i]);
	}
}

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