백준 15439 - Java

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Bera {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        int result = N*(N-1);
        System.out.println(result);
    }
}