import std.experimental.all;

T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;

// 3.3 sec で AC
int calc(int[][] g) {
    int rows = cast(int)g.length;
    int cols = cast(int)g[0].length;

    auto delta = [[-1, 0], [1, 0], [0, -1], [0, 1]];

    void fill(int row, int col, int[][] g, int[][] used) {
        assert(g[row][col] == 1);

        auto q = DList!(int)();
        // [row, col] で配列生成すると TLE (2 sec 近く遅くなる)
        q.insertBack((row << 16) | col);
        while (!q.empty) {
            auto a = q.front;
            q.removeFront();

            int r = (a >> 16), c = a & 0xffff;
            if (used[r][c]++) continue;
            foreach (d; delta) {
                int r2 = r + d[0];
                int c2 = c + d[1];
                if (!(0 <= r2 && r2 < rows && 0 <= c2 && c2 < cols)) continue;
                if (g[r2][c2] == 0 || used[r2][c2]) continue;

                q.insertBack((r2 << 16) | c2);
            }
        }
    }

    int ans = 0;
    auto used = new int[][](rows, cols);
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            if (used[i][j]) continue;
            if (g[i][j] == 1) {
                ans++;
                fill(i, j, g, used);
            }
        }
    }
    return ans;
}

int calc2(int[][] g) {
    int rows = cast(int)g.length;
    int cols = cast(int)g[0].length;

    int toIndex(int r, int c) {
        return r * cols + c;
    }

    auto uf = new UnionFind(rows * cols);
    int one = 0;
    int uniteCount = 0;
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            if (g[i][j] == 0) continue;

            one++;
            if (i > 0 && g[i-1][j] == 1) {
                int a = toIndex(i, j);
                int b = toIndex(i-1, j);
                if (uf.unite(a, b)) uniteCount++;
            }

            if (j > 0 && g[i][j-1] == 1) {
                int a = toIndex(i, j);
                int b = toIndex(i, j-1);
                if (uf.unite(a, b)) uniteCount++;
            }
        }
    }
    return one - uniteCount;
}

void main() {
    auto hw = readints;
    int h = hw[0], w = hw[1];
    auto g = new int[][](h, w);
    for (int i = 0; i < h; i++) {
        g[i][] = readints;
    }

    // writeln(calc(g));// AC 3.2 sec
    writeln(calc2(g));
}

class UnionFind {
    private int[] _data;

    this(int n) {
        _data  = new int[](n + 1);
        _data[] = -1;
    }

    int root(int a) {
        if (_data[a] < 0) return a;
        return _data[a] = root(_data[a]);
    }

    bool unite(int a, int b) {
        /*
        int ra = root(a);
        int rb = root(b);
        if (ra == rb) return false;
        // ra に rb を繋げる
        _data[ra] += _data[rb];
        _data[rb] = ra;
        return true;
        */
        int ra = root(a);
        int rb = root(b);
        if (ra != rb) {
            if (_data[rb] < _data[ra]) swap(ra, rb);
            _data[ra] += _data[rb];
            _data[rb] = ra;
        }
        return ra != rb;
    }

    bool isSame(int a, int b) {
        return root(a) == root(b);
    }

    /// a が属する集合のサイズ
    int groupSize(int a) {
        return -_data[root(a)];
    }
}