using System;

namespace No460{
    public class Program{
        public static void Main(string[] args){
            var sr = new StreamReader();
            //---------------------------------
            var M = sr.Next<int>();
            var N = sr.Next<int>();
            var A = sr.Next<int>(M, N);
            var a = new int[M, N].ToJaggedArray();

            Func<int, int, bool> isInside = (x, y) => 0 <= x && x < N && 0 <= y && y < M;
            Action<int, int> flip = (x, y) =>{
                for(var i = y - 1; i <= y + 1; i++){
                    for(var j = x - 1; j <= x + 1; j++){
                        if(isInside(j, i)) a[i][j] = 1 - a[i][j];
                    }
                }
            };

            Func<bool> isSame = () =>{
                var ret = true;
                for(var i = 0; i < M; i++){
                    for(var j = 0; j < N; j++){
                        ret &= A[i][j] == a[i][j];
                    }
                }
                return ret;
            };

            Func<int, bool> isOk = index => {
                var x = index % N;
                var y = index / N;
                return A[y][x] == a[y][x];
            };

            Func<int, int, int> dfs = null;
            dfs = (index, cnt) =>{
                if(index - N - 2 >= 0) if(!isOk(index - N - 2)) return int.MaxValue;
                if(index == M * N) return isSame() ? cnt : int.MaxValue;
                var x = index % N;
                var y = index / N;
                var ret = int.MaxValue;
                ret = Math.Min(ret, dfs(index + 1, cnt));
                flip(x, y);
                ret = Math.Min(ret, dfs(index + 1, cnt + 1));
                flip(x, y);
                return ret;
            };

            var res = dfs(0, 0);
            Console.WriteLine(res != int.MaxValue ? res.ToString() : "Impossible");
            //---------------------------------
        }
    }

    public static class ExMethod{
        public static T[][] ToJaggedArray<T>(this T[,] src){
            var x = src.GetLength(1);
            var y = src.GetLength(0);
            var ret = new T[y][];

            for(var i = 0; i < y; i++){
                ret[i] = new T[x];
                for(var j = 0; j < x; j++){
                    ret[i][j] = src[i, j];
                }
            }

            return ret;
        }
    }

    public class StreamReader{
        private readonly char[] _c = {' '};
        private int _index = -1;
        private string[] _input = new string[0];
        private readonly System.IO.StreamReader _sr = new System.IO.StreamReader(Console.OpenStandardInput());

        public T Next<T>(){
            if(_index == _input.Length - 1){
                _index = -1;
                while(true){
                    string rl = _sr.ReadLine();
                    if(rl == null){
                        if(typeof(T).IsClass) return default(T);
                        return (T)typeof(T).GetField("MinValue").GetValue(null);
                    }
                    if(rl != ""){
                        _input = rl.Split(_c, StringSplitOptions.RemoveEmptyEntries);
                        break;
                    }
                }
            }
            return (T)Convert.ChangeType(_input[++_index], typeof(T), System.Globalization.CultureInfo.InvariantCulture);
        }

        public T[] Next<T>(int x){
            var ret = new T[x];
            for(var i = 0; i < x; ++i) ret[i] = Next<T>();
            return ret;
        }

        public T[][] Next<T>(int y, int x){
            var ret = new T[y][];
            for(var i = 0; i < y; ++i) ret[i] = Next<T>(x);
            return ret;
        }
    }
}