const rows = 13;
let line_number = 1;
if (rows <= 13 && rows >=1) {
for (let i = 1; i <= rows * 2; i += 2) {
if (line_number % 2 == 1) {
console.log(String.fromCharCode(i + 64) + " " + String.fromCharCode(i + 65));
} else {
console.log(String.fromCharCode(i + 65) + " " + String.fromCharCode(i + 64));
}
line_number++;
}
}
/*
run:
"A B"
"D C"
"E F"
"H G"
"I J"
"L K"
"M N"
"P O"
"Q R"
"T S"
"U V"
"X W"
"Y Z"
*/