#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++)

using namespace std;
typedef long long int ll;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef pair<int, int> PI;
const ll mod = 1e9 + 7;

int gauss_elim_i64(VL a, ll b) {
  int n = a.size();
  int c = 0;
  vector<int> revmap;
  REP(r, 0, 64) {
    if (c >= n) {
      break;
    }
    int c2 = -1;
    REP(i, c, n) {
      if (a[i] & (1LL << r)) {
	c2 = i;
	break;
      }
    }
    if (c2 < 0) {
      revmap.push_back(-1);
      continue;
    }
    if (c != c2) {
      swap(a[c], a[c2]);
    }
    ll rm = a[c] & -(1LL << r) << 1;
    a[c] ^= rm;
    REP(k, c + 1, n) {
      if (a[k] & (1LL << r)) {
	a[k] ^= rm;
      }
    }
    if (b & (1LL << r)) {
      b ^= rm;
    }
    revmap.push_back(c);
    c++;
  }
  // recover
  if (0) {
    REP(i, 0, revmap.size()) {
      cout << "revmap: " << i << " => " << revmap[i] << endl;
    }
  }
  int rank = revmap.size();
  ll x = 0;
  for (int i = rank - 1; i >= 0; --i) {
    if (b & 1LL << i) {
      int c = revmap[i];
      if (c < 0) {
	return -1;
      }
      b ^= a[c];
      x |= 1LL << c;
    }
  }
  return b == 0 ? __builtin_popcountll(x) : -1;
}

int solve(ll board, int m, int n) {
  VL basis;
  REP(i, 0, m) {
    REP(j, 0, n) {
      ll v = 0;
      REP(dx, -1, 2) {
	REP(dy, -1, 2) {
	  int ni = i + dx;
	  int nj = j + dy;
	  if (ni < 0 || ni >= m || nj < 0 || nj >= n) {
	    continue;
	  }
	  v |= 1 << (ni * n + nj);
	}
      }
      basis.push_back(v);
    }
  }
  int rank = gauss_elim_i64(basis, board);
  return rank;
}

int main(void){
  int m, n;
  cin >> m >> n;
  ll board = 0;
  REP(i, 0, m) {
    REP(j, 0, n) {
      int tmp;
      cin >> tmp;
      board |= tmp << (i * n + j);
    }
  }
  int result = solve(board, m, n);
  if (result < 0) {
    cout << "Impossible" << endl;
  } else {
    cout << solve(board, m, n) << endl;
  }
}