using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, m) = (c[0], c[1]);
        var s = SList(n);
        var count = new int[m];
        foreach (var si in s) for (var i = 0; i < si.Length; ++i) if (si[i] == 'o') ++count[i];
        WriteLine(n - count.Min() + 1);
    }
}