import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        int count = 0;
        int total = n;
         while (total > 1){
             total = total - 1;
             count++;
         }
        count = count * m;
        System.out.println(count);
    }
}