Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	resolve()
}

func resolve() {
	results := []int{}
	for true {
		w, h := scanInt(sc), scanInt(sc)
		if w == 0 && h == 0 {
			break
		}
		grid := make([][]int, h)
		for i := 0; i < h; i++ {
			grid[i] = make([]int, w)
			for j := 0; j < w; j++ {
				grid[i][j] = scanInt(sc)
			}
		}
		num := 0
		for i := range loop0(h) {
			for j := range loop0(w) {
				start := pos{y: i, x: j}
				if grid[start.y][start.x] == 0 {
					continue
				}
				num++
				_dfs(grid, w, h, start)
			}
		}
		results = append(results, num)
	}
	for _, v := range results {
		fmt.Println(v)
	}
	return
}

func _dfs(grid [][]int, w, h int, start pos) {
	grid[start.y][start.x] = 0
	for _, df := range []pos{
		pos{1, 0}, pos{-1, 0},
		pos{0, -1}, pos{0, 1},
		pos{1, 1}, pos{-1, -1},
		pos{-1, 1}, pos{1, -1},
	} {
		np := addPos(start, df)
		if np.y < 0 || h <= np.y || np.x < 0 || w <= np.x {
			continue
		}
		if grid[np.y][np.x] == 0 {
			continue
		}
		_dfs(grid, w, h, np)
	}
}

type pos struct{ x, y int }

func addPos(p, d pos) pos {
	return pos{
		x: p.x + d.x,
		y: p.y + d.y,
	}
}

func loop0(n int) chan int {
	return loop(0, n-1, 1)
}

func loop1(n int) chan int {
	return loop(1, n, 1)
}

func loop(s, e, d int) chan int {
	ch := make(chan int)
	go func() {
		for i := s; i <= e; i += d {
			ch <- i
		}
		close(ch)
	}()
	return ch
}

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

Python: #!python
# -*- coding: utf-8 -*-

import sys

import numpy as np

sys.setswitchinterval(10**8)


next_s = ((-1, 1), (0, 1), (1, 1),
          (-1, 0), (1, 0),
          (-1, -1), (0, -1), (1, -1))


def DFS(x, y):
    if not (0 <= x < W and 0 <= y < H):
        return
    if not map_[y, x]:
        return

    map_[y, x] = 0

    for dx, dy in next_s:
        DFS(x + dx, y + dy)


while True:
    W, H = map(int, input().split())
    if W == 0 and H == 0:
        break

    map_ = np.array([list(map(int, input().split())) for h in range(H)])
    # print(map_)
    island_num = 0
    while np.amax(map_):
        x = np.argmax(map_) % W
        y = np.argmax(map_) // W
        # print(map_)
        # print("x: {} | y: {}".format(x, y))
        DFS(x, y)
        island_num += 1

    print(island_num)

Python: class Union_find():

    def __init__(self, num):
        self.num = num
        self.par = list(range(num))
        self.rank = [0]*num

    def find(self, x):
        px = self.par[x]
        if px == x:
            return x
        else:
            rx = self.find(px)
            self.par[x] = rx
            return rx

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x != y:
            if self.rank[x] > self.rank[y]:
                self.par[y] = x
            else:
                self.par[x] = y
                if self.rank[x] == self.rank[y]:
                    self.rank[y] = self.rank[y] + 1
        return self

    def same(self, x, y):
        return self.find(x) == self.find(y)

class Group_map():
    #dx, dyは原点対象となる要素を省く
    def __init__(self, H, W, dx, dy, Mat):
        self.H = H
        self.W = W
        self.dx = dx
        self.dy = dy
        self.Mat = Mat
        self.group = Union_find(H*W)

    def to_num(self, i, j):
        return i*(self.W) + j

    def grouping(self):
        for i in range(self.H):
            for j in range(self.W):
                for k in range(len(self.dx)):
                    (ni, nj) = (i + self.dx[k], j + self.dy[k])
                    if ni in range(self.H) and nj in range(self.W) and self.Mat[i][j] == self.Mat[ni][nj]:
                        self.group.union(self.to_num(i, j), self.to_num(ni, nj))
        return self

    def num_group(self, k):
        self.grouping()
        l = set()
        for i in range(self.H):
            for j in range(self.W):
                if self.Mat[i][j] == k:
                    l.add(self.group.find(self.to_num(i, j)))
        return len(l)

    def same(self, x, y):
        return self.group.same(self.to_num(x[0], x[1]), self.to_num(y[0], y[1]))

(w, h) = map(int, input().split(" "))
while w != 0 and h != 0:
    Map = []
    for i in range(h):
        Map.append(list(map(int, input().split(" "))))
    g = Group_map(h, w, [1, 1, 1, 0], [-1, 0, 1, 1], Map)
    print(g.num_group(1))
    (w, h) = map(int, input().split(" "))

Python: def solver():
    w, h = map(int, input().split())
    if w == 0 and h == 0:
        return None
    islands = set()
    counter = 2
    c = [[0] + [int(x) for x in input().split()] + [0]  for _ in range(h)]
    c = [[0 for _ in range(w+2)]] + c + [[0 for _ in range(w+2)]]
    for i in range(1, h+1):
        for j in range(1, w+1):
            if c[i][j] > 0:
                neighbour = {c[i-1][j-1], c[i-1][j], c[i-1][j+1], c[i][j-1]}
                if max(neighbour) > 1:
                    c[i][j] = max(neighbour)
                    if len(neighbour - {0}) > 1:
                        islands -= {max(neighbour)}
                else:
                    c[i][j] = counter
                    islands |= {counter}
                    counter += 1
    return len(islands)

outputs = []
while(True):
    ans = solver()
    if ans == None:
        break
    outputs.append(ans)
print('\n'.join(map(str, outputs)))

Python: # Union Find
#0オリジン以下注意

#xの根を求める
def find(x):
    if par[x] < 0:
        return x
    else:
        par[x] = find(par[x])
        return par[x]
    
def unite(x, y):
    x = find(x)
    y = find(y)
    
    if x == y:
        return False
    else:
        #sizeの大きい方がx
        if par[x] > par[y]:
            x, y = y, x
        par[x] += par[y] #ここで集合の個数を更新している
        par[y] = x
        return True
    
#xとyが同じ集合に含まれているかどうかを判定(同じ集合にあればTrue)
def same(x, y):
    return find(x) == find(y)

#xが属する集合の個数
def size(x):
    return -par[find(x)]

#初期化
#根なら-size, 子なら親の頂点
################以下にコードを書く

while True:
    w, h = map(int, input().split())
    par = [-1]*(w*h)
    if (w, h) == (0, 0):
        break
    li = []
    for i in range(h):
        li.append(list(map(int, input().split())))
    for i in range(h):
        for j in range(w-1):
            if li[i][j] == li[i][j+1]:
                unite(w*i+j, w*i+j+1)
    for j in range(w):
        for i in range(h-1):
            if li[i][j] == li[i+1][j]:
                unite(w*i+j, w*i+j+w)
    for i in range(h):
        for j in range(w):
            I1 = i+1
            I2 = i-1
            J = j+1
            if 0 <= I1 and I1<h and 0<=J and J<w:
                if li[i][j] == 1 and li[I1][J] == 1:
                    unite(w*i+j, w*I1+J)
            if 0 <= I2 and I2<h and 0<=J and J<w:
                if li[i][j] == 1 and li[I2][J] == 1:
                    unite(w*i+j, w*I2+J)

                    
    #島を数える
    #陸のリスと
    li_riku = []
    for i in range(h):
        for j in range(w):
            if li[i][j]==1:
                li_riku.append(w*i+j)
    li_island = []
    sum_size = len(li_riku)
    for i in li_riku:
        k = find(i)
        if k not in li_island:
            li_island.append(k)
    print(len(li_island))