#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Trim().Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

var h = I<int>();
var w = I<int>();
var g = new int[h, w];
for (var i = 0; i < h; i++) for (var j = 0; j < w; j++)
{
    g[i, j] ^= I<int>();
}
for (var i = 0; i < h - 1; i++)
{
    for (var j = 0; j < w - 1; j++)
    {
        if (g[i, j] == 1)
        {
            g[i, j] ^= 1;
            g[i + 1, j] ^= 1;
            g[i, j + 1] ^= 1;
            g[i + 1, j + 1] ^= 1;
        }
    }
}
var ic = 0;
var jc = 0;
var corner = g[h - 1, w - 1];
for (var i = 0; i < h; i++) ic += g[i, w - 1];
for (var j = 0; j < w; j++) jc += g[h - 1, j];
var min = Math.Min(ic, jc);
var left = Math.Max(ic, jc) - min;
var ans = min + left + (corner + min) % 2;
Console.WriteLine(ans);