import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashSet;
import java.util.InputMismatchException;

public class Main {
	static long mod=(long)(1e9+7);
	static ArrayList<Integer> al[];
	static boolean visited[];
	static int v=0;
	public static void main(String args[]) throws IOException{
		new Thread(null,new Runnable(){
			public void run(){
				new Main().run();
			}
		},"1",1<<23).start();

	}
	protected void run() {
		// TODO Auto-generated method stub
		InputReader in 		= new InputReader(System.in);
		OutputWriter out	=	new OutputWriter(System.out);
		long n=Long.parseLong(in.readString());
		long m=Long.parseLong(in.readString());
		long ans=0;
			ans=n*m-1;
			out.printLine(ans);
		out.flush();
		out.close();
	}



}

class node implements Comparable<node>{
	public node(int i, int j) {
		x=i;
		index=j;
	}

	int x,index;

	@Override
	public int compareTo(node o) {
		return Integer.compare(x, o.x);
	}

	public int hashCode(){
		return x*31+index*17;
	}
	public boolean equals(Object o){
		node od=(node)o;
		return x==od.x && index==od.index;
	}
}
/*class node implements Comparable<node>{
    	int d,w;
    	node(int d,int w){
    		this.d=d;
    		this.w=w;
    	}
    	@Override
    	public int compareTo(node o) {
    		// TODO Auto-generated method stub
    		if( w<o.w)
    			return -1;
    		return  w==o.w?0:1;
    	}

    	@Override public boolean equals(Object other) {
    		if (!(other instanceof node)) {
    			return false;
    		}
    		node otherNode = (node) other;
    		return d == otherNode.d && w == otherNode.w;
    	}

    	@Override public int hashCode() {
    		return d * 31 + w * 17; // For example...
    	}
    }*/

class InputReader {

	private InputStream stream;
	private byte[] buf = new byte[1024];
	private int curChar;
	private int numChars;
	private SpaceCharFilter filter;

	public InputReader(InputStream stream) {
		this.stream = stream;
	}

	public int read() {
		if (numChars == -1)
			throw new InputMismatchException();
		if (curChar >= numChars) {
			curChar = 0;
			try {
				numChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (numChars <= 0)
				return -1;
		}
		return buf[curChar++];
	}

	public int readInt() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public String readString() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isSpaceChar(c));
		return res.toString();
	}

	public boolean isSpaceChar(int c) {
		if (filter != null)
			return filter.isSpaceChar(c);
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	public String next() {
		return readString();
	}

	public interface SpaceCharFilter {
		public boolean isSpaceChar(int ch);
	}
}

class OutputWriter {
	private final PrintWriter writer;

	public OutputWriter(OutputStream outputStream) {
		writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
	}

	public OutputWriter(Writer writer) {
		this.writer = new PrintWriter(writer);
	}

	public void print(Object...objects) {
		for (int i = 0; i < objects.length; i++) {
			if (i != 0)
				writer.print(' ');
			writer.print(objects[i]);
		}
	}

	public void printLine(Object...objects) {
		print(objects);
		writer.println();
	}

	public void close() {
		writer.close();
	}

	public void flush() {
		writer.flush();
	}

}

class IOUtils {

	public static int[] readIntArray(InputReader in, int size) {
		int[] array = new int[size];
		for (int i = 0; i < size; i++)
			array[i] = in.readInt();
		return array;
	}

}