Problem:
﻿Score: 100 points

Problem Statement

There is a farm whose length and width are A yard and B yard, respectively. A farmer, John, made a vertical road and a horizontal road inside the farm from one border to another, as shown below: (The gray part represents the roads.)

What is the area of this yard excluding the roads? Find it.

Note

It can be proved that the positions of the roads do not affect the area.

Constraints

A is an integer between 2 and 100 (inclusive).

B is an integer between 2 and 100 (inclusive).

Input

Input is given from Standard Input in the following format:

A B

Output

Print the area of this yard excluding the roads (in square yards).

Sample Input 1

2 2

Sample Output 1

1

In this case, the area is 1 square yard.

Sample Input 2

5 7

Sample Output 2

24

In this case, the area is 24 square yards.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)


using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace AtCoder
{
	// http://abc106.contest.atcoder.jp/tasks/abc106_a
	public class Abc106_a
	{
#if !Development
		public static void Main(string[] args)
		{
			Abc106_a.Solve(args);
		}
#endif

		public static void Solve(string[] args)
		{
			var line1 = ReadLineInt();
			var a = line1[0];
			var b = line1[1];

			var answer = a * b - a - b + 1;

			Console.WriteLine(answer);
		}

		public static List<string> ReadLineString() { return Console.ReadLine().Split(' ').ToList(); }
		public static List<int> ReadLineInt() { return Console.ReadLine().Split(' ').Select(str => int.Parse(str)).ToList(); }
		public static int ReadLineIntOne() { return Console.ReadLine().Split(' ').Select(str => int.Parse(str)).First(); }
		public static List<int> MultiReadLineInt(int lineNum) { return Enumerable.Range(0, lineNum).Select(_ => ReadLineIntOne()).ToList(); }
	}
}