// yukicoder: No.697 池の数はいくつか
// 2019.7.12 bal4u

#include <stdio.h>

#if 1
#define gc() getchar_unlocked()
#else
#define gc() getchar()
#endif

int in() {   // 非負整数の入力
	int n = 0, c = gc();
	do n = 10 * n + (c & 0xf); while ((c = gc()) >= '0');
	return n;
}

/* UNION-FIND library */
#define MAX 9000005
int id[MAX], size[MAX];
void init(int n) { int i; for (i = 0; i < n; i++) id[i] = i, size[i] = 1; }
int root(int i) { while (i != id[i]) id[i] = id[id[i]], i = id[i]; return i; }
int connected(int p, int q) { return root(p) == root(q); }
void unite(int p, int q) {
    int i = root(p), j = root(q); if (i == j) return;
    if (size[i] < size[j]) id[i] = j, size[j] += size[i]; else id[j] = i, size[i] += size[j];
}

int H, W;
char t[2][3003];

int main()
{
	int k0, k, p0, p, r, c, ans, land;

	H = in(), W = in();
	init(H*W);
	ans = land = 0;
	for (c = 0; c < W; c++) {
		t[0][c] = gc() & 1, gc();
		if (!t[0][c]) land++;
		else if (c && (t[0][c] & t[0][c-1])) unite(c, c-1);
	}
	p0 = 0, p = W, k0 = 0, k = 1;
	for (r = 1; r < H; r++) {
		for (c = 0; c < W; c++) {
			t[k][c] = gc() & 1, gc();
			if (!t[k][c]) land++;
			else {
				if (t[k][c] & t[k0][c]) unite(p0+c, p+c);
				if (c > 0 && (t[k][c] & t[k][c-1])) unite(p+c, p+c-1);
			}
		}
		p0 += W, p += W, k0 = k, k = !k;
	}
	
	ans = 0;
	k = H*W; while (k--) if (root(k) == k) ans++;
	printf("%d\n", ans - land);
	return 0;
}