var input = require('fs').readFileSync('/dev/stdin', 'utf8');
var Arr=input.split("\n");
var str="";
for(var i=0;i<Arr.length;i++){
var arr=Arr[i].split(" ").map(Number);
var h=arr[0];
var w=arr[1];
if(h===0 && w===0)break;
if(i!==0)str+="\n";
var W0=(Array(w+1).join("#.")).slice(0,w)+"\n";
var W1=(Array(w+1).join(".#")).slice(0,w)+"\n";
for(var j=0;j<h;j++)str+=(j%2===0)?W0:W1;
}
console.log(str);