function main(input) {
  var temp = input.split('\n');
  for (var i = 0; i < temp.length; i++) {
    var data = temp[i].split(' ').map(Number);
    var height = data[0];
    var width = data[1];
    if (height == 0 && width == 0)
      break;

    var answer = "";
    for (var j = 0; j < height; j++) {
      for (var k = 0; k < width; k++) {
        if ((j + 1) % 2 == 1) {
          if ((k + 1) % 2 == 1) {
            answer += "#";
          } else {
            answer += '.';
          }
        } else {
          if ((k + 1) % 2 == 1) {
            answer += ".";
          } else {
            answer += '#';
          }
        }
      }
      answer += '\n';
    }
    console.log(answer.trim() + '\n');
  }
}

var x = require('fs').readFileSync('/dev/stdin', 'utf-8');
main(x);
