#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iterator>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
#include <fstream>
#include <iomanip>
#include <cassert>
//#include <utility>
//#include <memory>
//#include <functional>
//#include <deque>
//#include <cctype>
//#include <ctime>
//#include <numeric>
//#include <list>
//#include <iomanip>

//#if __cplusplus >= 201103L
//#include <array>
//#include <tuple>
//#include <initializer_list>
//#include <forward_list>
//
//#define cauto const auto&
//#else

//#endif

using namespace std;


typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vint;
typedef vector<vector<int> > vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long> > vvll, vvLL;

#define VV(T) vector<vector< T > >



template <class F, class T>
void convert(const F &f, T &t){
    stringstream ss;
    ss << f;
    ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(),(v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x)  cout << #x << " = " << (x) << endl;
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#else
#define dump(x) 
#define debug(x) 
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x,y) x=max(x,y)
#define mins(x,y) x=min(x,y)


vvint vv;
int h,w;

template <class T>
void initvv(vector<vector<T> > &v, int a, int b, const T &t = T()){
    v.assign(a, vector<T>(b, t));
}

bool inside(int y, int x){
	return 0<=y&&y<h&&0<=x&&x<w;
}

void change(int y, int x, vvint &vv){
	rep(i,3){
		rep(j,3){
			if(inside(y-1+i, x-1+j)){
				vv[y-1+i][x-1+j]^=1;
			}
		}
	}
}

int check(){
	int ret = 0;
	vvint tmp = vv;
	rep(i,h){
		rep(j,w){
			if(tmp[i][j]){
				if(!inside(i+1,j+1)) return INF;
				ret++;
				change(i+1, j+1, tmp);
			}
		}
	}
	return ret;
}


int dfs(int y, int x){
	if(x==w) return dfs(1, 0);
	if(y == h) return check();

	int ret = INF;
	if(y==0){
		mins(ret, dfs(y,x+1));
		change(0,x,vv);
		mins(ret, dfs(y,x+1)+1);
		change(0,x,vv);
	}
	else{
		mins(ret, dfs(y+1,x));
		change(y,0,vv);
		mins(ret, dfs(y+1,x)+1);
		change(y,0,vv);
	}
	return ret;
}


void mainmain(){
	cin>>h>>w;
	initvv(vv,h,w);
	rep(i,h) rep(j,w) cin>>vv[i][j];
	int ans = dfs(0,0);
	cout << (ans>=INF/2?"Impossible":to_string(ans)) << endl;
}


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout<<fixed<<setprecision(20);
    mainmain();
}