#include <iostream>
using namespace std;

int main(){
    int H, W;
    cin >> H >> W;
    while ((H!=0)||(W!=0)){
        for(int i=0; i<H*W; i++){
            if(i+1%W==0) cout << endl;
            if(i%2==0) cout << "#";
            else cout << ".";
        }
        cout << endl << endl;
        cin >> H >> W
    }
    return 0;
}
