https://www.e-olymp.com/az/problems/593

/*
    Author: Kanan Asgarli
    https://www.e-olymp.com/az/problems/593
*/
#include <iostream>
#include <algorithm>
using namespace std;
int n, m, f;
int main()
{
    cin>>n>>m;
    if(n%2 == 0)
        f = 1;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if((i-f)%2 == 1){
                if(j%2 == 1)
                    cout<<".";
                else
                    cout<<"X";
            }
            else{
                if(j%2 == 1)
                    cout<<"X";
                else
                    cout<<".";
            }
        }
        cout<<endl;
    }
    return 0;
}