const createStripe = function(length, pattern) {
    var stripe = '';
    for (var i = 0; i < length; i++) {
        stripe += pattern[i % pattern.length];
    }
    return stripe;
};

const createChessboard = function (h, w) {
    const pattern = ['#', '.'];
    const lines = [createStripe(w, pattern) + '\n', createStripe(w, pattern.reverse()) + '\n'];
    return createStripe(h, lines);
};

const isZero = function (a) {return 0 === a;};

const chunk = require('fs').readFileSync('/dev/stdin', 'utf8');
const lines = chunk.split('\n');

lines.some(function (line) {
    var hw = line.split(' ').map(Number);
    if (hw.every(isZero)) {
        return true;
    }
    console.log(createChessboard(hw[0], hw[1]));
});