Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}

func getNextUint64(scanner *bufio.Scanner) uint64 {
	i, _ := strconv.ParseUint(getNextString(scanner), 10, 64)
	return i
}

func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}

func main() {
	fp := os.Stdin
	wfp := os.Stdout
	cnt := 0

	if os.Getenv("MASPY") == "ますピ" {
		fp, _ = os.Open(os.Getenv("BEET_THE_HARMONY_OF_PERFECT"))
		cnt = 0
	}
	if os.Getenv("MASPYPY") == "ますピッピ" {
		wfp, _ = os.Create(os.Getenv("NGTKANA_IS_GENIUS10"))
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(wfp)
	for solve(scanner, writer) {

	}
	for i := 0; i < cnt; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
	writer.Flush()
}

func solve(scanner *bufio.Scanner, writer *bufio.Writer) bool {
	sol := solver{}
	sol.w = getNextInt(scanner)
	sol.h = getNextInt(scanner)
	if sol.w == 0 && sol.h == 0 {
		return false
	}
	sol.land = makeInts(sol.h, sol.w)
	for y := 0; y < sol.h; y++ {
		for x := 0; x < sol.w; x++ {
			sol.land[y][x] = getNextInt(scanner)
		}
	}
	ans := 0
	for y := 0; y < sol.h; y++ {
		for x := 0; x < sol.w; x++ {
			if sol.land[y][x] == 0 {
				continue
			}
			ans++
			sol.dfs(y, x)
		}
	}
	fmt.Fprintln(writer, ans)
	return true
}

type solver struct {
	w, h int
	land [][]int
}

func (sol *solver) dfs(y, x int) {
	if y < 0 {
		return
	}
	if y >= sol.h {
		return
	}
	if x < 0 {
		return
	}
	if x >= sol.w {
		return
	}
	if sol.land[y][x] == 0 {
		return
	}
	sol.land[y][x] = 0
	dy := [8]int{-1, -1, -1, 0, 0, 1, 1, 1}
	dx := [8]int{-1, 0, 1, -1, 1, -1, 0, 1}
	for i := 0; i < 8; i++ {
		sol.dfs(y+dy[i], x+dx[i])
	}
}
func makeInts(h, w int) [][]int {
	index := make([][]int, h, h)
	data := make([]int, h*w, h*w)
	for i := 0; i < h; i++ {
		index[i] = data[i*w : (i+1)*w]
	}
	return index
}

C++: #include<bits/stdc++.h>
using namespace std;
using ll=long long;
using vec=vector<ll>;
using mat=vector<vec>;
#define For(i,a,b) for(i=a;i<b;i++)
#define rep(i,N) For(i,0,N)
#define rep1(i,N) For(i,1,N)
#define all(v) (v).begin(),(v).end()
#define allr(v) (v).rbegin(),(v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define mod 1000000007
using datas=pair<ll,ll>;
using tdata=pair<datas,ll>;

long mmid(long a,long b,long c){return a<b?(b<c?b:max(a,c)):(b>c?b:min(a,c));}

ll modinv(ll a) {
  ll b=mod,u=1,v=0,t;
  while(b){
    t=a/b;
    a-=t*b; swap(a,b);
    u-=t*v; swap(u,v);
  }
  return (u+mod)%mod;
}

ll moddevide(ll a,ll b){return (a*modinv(b))%mod;}

ll modncr(ll n,ll r){
  ll i,plus=1;
  rep(i,r){
    plus=(plus*(n-i))%mod;
    plus=moddevide(plus,i+1);
  }
  return plus;
}

ll modncrlistp[200000],modncrlistm[200000];

ll modncrs(ll n,ll r){
  ll i,j;
  if(modncrlistp[n]==0){
    for(i=n;i>=0;i--){
      if(modncrlistp[i])break;
    }
    if(i<0){
      modncrlistp[0]=1;
      rep1(i,n+1){
        modncrlistp[i]=(modncrlistp[i-1]*i)%mod;
      }
    }else{
      For(j,i+1,n+1){
        modncrlistp[j]=(modncrlistp[j-1]*j)%mod;
      }
    }
  }
  if(modncrlistm[n]==0){
    for(i=n;i>=0;i--){
      if(modncrlistm[i])break;
    }
    if(i<0){
      modncrlistm[0]=1;
      rep1(i,n+1){
        modncrlistm[i]=(modncrlistm[i-1]*modinv(i))%mod;
      }
    }else{
      For(j,i+1,n+1)modncrlistm[j]=(modncrlistm[j-1]*modinv(j))%mod;
    }
  }
  return (((modncrlistp[n]*modncrlistm[r])%mod)*modncrlistm[n-r])%mod;
}

ll euclidean_gcd(ll a, ll b) {
  if(a<b) return euclidean_gcd(b, a);
  ll r;
  while ((r=a%b)){a=b;b=r;}
  return b;
}

ll countdigits(ll n){
  ll ans=0;
  while(n){n/=10;ans++;}
  return ans;
}

ll sumdigits(ll n){
  ll ans=0;
  while(n){ans+=n%10;n/=10;}
  return ans;
}

void printmap(vector<ll>& a,ll H,ll W){
  ll i,j;
  For(i,0,H+2){
    For(j,0,W+2){cout<<a[i*(W+2)+j];}
    cout<<endl;
  }
}
void inputmap(vector<ll>& a,ll H,ll W){
  ll i,j;
  string ss;
  For(i,1,H+1){
    cin>>ss;
    For(j,1,W+1){
      if(ss[j-1]=='#'){
        a[i*(W+2)+j]=1;
      }else{
        a[i*(W+2)+j]=0;
      }
    }
  }
}
ll lpow(ll a,ll b){
  ll i,res=1;
  rep(i,b){
    res*=a;
  }
  return res;
}

struct unionfind{
  vector<ll> par,treesize;
  unionfind(ll N){
    par.resize(N);
    for(ll i=0;i<N;i++)par[i]=i;
    treesize.resize(N);
    for(ll i=0;i<N;i++)treesize[i]=1;
  }
  ll root(ll x){
    ll r;
    if(par[x]==x)return x;
    r=root(par[x]);
    if(par[x]!=r){
      treesize[r]+=treesize[x];
      treesize[x]=0;
      par[x]=r;
    }
    return r;
  }
  void unite(ll x,ll y){
    ll px=root(x);
    ll py=root(y);
    if(px!=py){
      par[px]=py;
      treesize[py]+=treesize[px];
      treesize[px]=0;
    }
  }
  bool parcheck(ll x,ll y){
    ll px=root(x);
    ll py=root(y);
    return px==py;
  }
  ll size(ll x){
    ll px=root(x);
    return treesize[px];
  }
};

int main(){
  while(1){
  ll i,j=0,N,M,cnt=0;
  cin>>M>>N;
  if(N+M==0)return 0;
  unionfind tree(N*M);
  vec v(N*M);
  set<ll> se;
  rep(i,N){
    rep(j,M){
      cin>>v[i*M+j];
      if(v[i*M+j]==1){
        if(i>0&&v[(i-1)*M+j]==1){
          tree.unite(i*M+j,(i-1)*M+j);
        }
        if(j>0&&v[i*M+j-1]==1){
          tree.unite(i*M+j,i*M+j-1);
        }
        if(i>0&&j>0&&v[(i-1)*M+j-1]==1){
          tree.unite(i*M+j,(i-1)*M+j-1);
        }
        if(i>0&&j<M-1&&v[(i-1)*M+j+1]==1){
          tree.unite(i*M+j,(i-1)*M+j+1);
        }
      }else{
        cnt++;
      }
    }
  }

  rep(i,N*M){
    ll K=tree.root(i);
    se.insert(K);
  }
  cout<<(ll)se.size()-cnt<<endl;
  se.clear();
}}

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

int num, land[1080][1080];
int xs[] = { 1, 1, 0, -1, -1, -1, 0, 1 };
int ys[] = { 0, 1, 1, 1, 0, -1, -1, -1 };
void dfs(int x, int y) {
    land[x][y] = 0;
    for (int i = 0; i < 8; i++) {
        int tx = x + xs[i];
        int ty = y + ys[i];
        if (land[tx][ty])dfs(tx, ty);
    }
}

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

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

using namespace std;

bool check(bool[50][50],pair<int, int>);
void rmv(bool[50][50], int, int);

int main(){
	for(int w, h; cin >> w >> h, w||h;){
		bool fld[50][50] = {0};
		int n;

		for(int i = 0; i < h; i++)
			for(int j = 0; j < w; j++)
				cin >> fld[i][j];

		for(n = 0; check(fld,make_pair(w, h)); n++);
		cout << n << endl;
	}
	return 0;
}


bool check(bool fld[50][50],pair<int, int> wide){
	for(int i = 0; i < wide.second; i++)
		for(int j = 0; j < wide.first; j++)
			if(fld[i][j]){
				rmv(fld, i, j);
				return true;
			}
	return false;
}

void rmv(bool fld[50][50], int y, int x){
	if(x >= 0 && y >= 0)
	if(fld[y][x]){
		fld[y][x] = false;
		for(int i = -1; i <= 1; i++)
			for(int j = -1; j <= 1; j++)
				rmv(fld, y+i , x+j);
	}
}