#include <iostream>
#include <vector>
#include <queue>
#include <set>

using namespace std;

int main() {
    int h, w;
    cin >> h >> w;

    vector<vector<string>> grid(h);
    for (int i = 0; i < h; ++i) {
        grid[i].resize(w);
        for (int j = 0; j < w; ++j) {
            cin >> grid[i][j];
        }
    }

    set<pair<int, int>> sensor;
    for (int j = 0; j < h; ++j) {
        for (int i = 0; i < w; ++i) {
            if (grid[j][i] == "1") {
                sensor.insert({i, j});
            }
        }
    }

    int count = 0;
    set<pair<int, int>> visited;
    while (!sensor.empty()) {
        queue<pair<int, int>> q;
        q.push(*sensor.begin());
        sensor.erase(sensor.begin()); 

        while (!q.empty()) {
            int x = q.front().first;
            int y = q.front().second;
            q.pop();
            
            if (sensor.count({x,y})){
                sensor.erase({x,y});
            }

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

            for (int i = 0; i < 4; ++i) {
                int nx = x + dx[i];
                int ny = y + dy[i];

                if (nx < 0 || nx >= w || ny < 0 || ny >= h) continue;
                if (grid[ny][nx] == "0") continue;
                if(visited.count({nx, ny}) == 0 && grid[ny][nx] == "1"){
                    visited.insert({nx, ny});
                    q.push({nx, ny});
                }
            }
        }
        count++;
    }
    
    cout << count << endl;
    return 0;
}