#include <iostream>
#include <vector>
#include <string>

using namespace std;

int main()
{
    int n, m, w = 0;
    cin >> n >> m;
    vector <string> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    for(;;)
    {
        bool x = 1;
        for(int i = 0; i < n - 1; i++)
        {
            x = x and (a[i] <= a[i + 1]);
        }
        if(x) break;
        else
        {
            int b = 0;
            bool t = 0;
            for(unsigned int i = 0; i < a.size(); i++)
            {
                for(int j = 0; j < n - 1; j++)
                {
                    if(a[j].substr(i, a.size()) > a[j + 1].substr(i, a.size()))
                    {
                        b = (int) i;
                        cout << b << endl;
                        w++;
                        t = 1;
                        break;
                    }
                }
                if(t) break;
            }
            for(int i = 0; i < n; i++)
            {
                a[i] = a[i].substr(0, b) + a[i].substr(b + 1, a.size());
            }
        }
    }
    cout << w;
    return 0;
}