<script>

            let n = prompt("Enter a number");
            let row, col;
            for(row = 1; row <= n; row++)
            {
                for(col = 1; col <= row; col++){
                    if ((col+row) % 2 == 0){
                        document.write("1")
                    }
                    else{
                        document.write("0");
                    }
                }
                document.write("<br>");
            }
            </script>