let content = '';
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', buf => {
  content += buf;
});
process.stdin.on('end', () => {
  const rects = content
    .trim()
    .split('\n')
    .map(line => line.split(' ').map(n => parseInt(n, 10)));

  for (const rect of rects) {
    if (rect[0] !== 0 || rect[1] !== 0) {
      console.log(drawReact(rect));
    }
  }
});

const drawReact = ([h, w]) => {
  let result = '';
  for (let i = 0; i < h; i++) {
    result += drawLine(w, i) + '\n';
  }

  return result;
};

const drawLine = (w, y) => {
  let result = '';
  for (let i = 0; i < w; i++) {
    result += getCharOn(i, y);
  }

  return result;
};

const getCharOn = (x, y) => {
  const chars = ['.', '#'];
  if (y % 2 === 0) {
    chars.reverse();
  }

  return chars[x % 2];
};
