Why doesn't it work?

Each integer you tried to enter surely started with this digit: 1. The read() method (in BufferedReader) always reads only one character, and not the character itself, but its Unicode code. Here is a table that shows which character has what kind of Unicode code: https://www.rapidtables.com/code/text/unicode-characters.html On this table press "1" and you can see it below the table in the green small box: Unicode = 31 (hexadecimal number). This number is 49 as a decimal number (see it in the small green "HTML code" field). This 49 is that number were shown by the output of your program. Try a number starting with 2 in your program, then the output will be 50. Write a text as input that starts with the uppercase "A": 65 will be the output. If you are copying a Chinese character to there: you will get a number around 20-30 thousand. Unicode tables contain all the existing characters in the world, and each character has a unique identification number. (There are tens of thousands.)

readLine () reads string( returns string) if u want to parse to number us Integer.parseInt( String str) read about methods u use

try to change int n = reader.read(); to String n = reader.readLine(); read() just reads one letter from the keyboard and saves it in an int. If you output that value you'll see the ASCII code of the input.