#include <bits/stdc++.h>
using namespace std;
constexpr int LAND = 10'000'000;

struct UnionFind{
    vector<int> data;
    UnionFind(int size) : data(size, -1){}
    void unite(int x, int y){
        x = root(x);
        y = root(y);
        if (x != y){
            if (data[y] < data[x]) swap(x, y);
            data[x] += data[y];
            data[y] = x;
        }
    }
    int root(int x) {return data[x] < 0 ? x : data[x] = root(data[x]);}
    int size(int x) {return -data[root(x)];}
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int H, W;
    cin >> H >> W;
    UnionFind uf(H * W);
    vector<char> pre(W);
    vector<char> cur(W);

    for (int h = 0 ; h < H; ++h){
        int hW = h * W;
        for (auto & c : cur) cin >> c;
        for (int w = 0; w < W; ++w){
            if (cur[w] == '1'){
                if (w > 0 and cur[w - 1] == '1') uf.unite(hW + w, hW + w - 1);
                if (h > 0 and pre[w] == '1') uf.unite(hW + w, hW + w - W);
            }else{
                uf.data[hW + w] = LAND;
            }
        }
        swap(pre, cur);
    }

    // count the number of ponds
    int ans = 0;
    for (auto v : uf.data) if (v < 0) ++ans;
    cout << ans << endl;

    return 0;
}