#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")


vector<int> uf;
int root(int u) {
  return (uf[u] < 0) ? u : (uf[u] = root(uf[u]));
}
bool connect(int u, int v) {
  u = root(u);
  v = root(v);
  if (u == v) return false;
  if (uf[u] > uf[v]) swap(u, v);
  uf[u] += uf[v];
  uf[v] = u;
  return true;
}


int M, N;
char B[1110][4110];

bitset<1024> A[4096];

int main() {
  for (; ~scanf("%d%d", &M, &N); ) {
    for (int i = 0; i < M; ++i) {
      scanf("%s", B[i]);
    }
    
    for (int u = 0; u < N; ++u) A[u].reset();
    for (int i = 0; i < M; ++i) for (int u = 0; u < N; ++u) if (B[i][u] == '1') A[u].set(i);
    
    uf.assign(N, -1);
    for (int u = 0; u < N; ++u) for (int v = u + 1; v < N; ++v) {
      if (root(u) != root(v) && !((A[u] & ~A[v]).any() && (~A[u] & A[v]).any())) {
        connect(u, v);
      }
    }
    int ans = 0;
    for (int u = 0; u < N; ++u) if (uf[u] < 0) ++ans;
    printf("%d\n", ans);
  }
  return 0;
}