const input = require('fs').readFileSync('/dev/stdin', 'utf8');
const arr = input.split('\n');
let str = '';
for(let i = 0; i < arr.length; i++){
  const elm = arr[i].split(" ").map(Number);
  const h = elm[0];
  const w = elm[1];
  if(h === 0 && w === 0) break;
  if(i !== 0) str += '\n';
  let evenLine = [];
  let oddLine = [];
  for(let j = 0; j < w; j++) evenLine.push(j % 2 === 0 ? '#':'.');
  for(let k = 0; k < w; k++) oddLine.push(k % 2 === 0 ? '.':'#');
  evenLine = evenLine.join('') + '\n';
  oddLine = oddLine.join('') + '\n';
  for(let l = 0; l < h; l++) str += l % 2 === 0 ? evenLine : oddLine;
}
console.log(str);
