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: Runtime Error)

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

namespace Astar {
    /*class Node {
        Node((int x, int y) _pos, int _status, int _cost, int _h, int _score, Node node) {
            pos = _pos;
            status = _status;
            cost = _cost;
            h = _h;
            score = _score;
            parent = node;
        }
        public (int x, int y) pos;
        public int status;
        public int cost;
        public int h;
        public int score;
        public Node parent;
    }*/

    /*
    class Program
    {
        static Node AddNode(int dx, int dy, int H, int W, int X, Node node, List<List<string>> s) {
            if (node.pos.x + dx < 0 || node.pos.y + dy < 0
                || node.pos.x + dx >= W || node.pos.y + dy >= H) return null;
            int cost;
            int status;
            switch(s[node.pos.y + dy][node.pos.x + dx]) {
                case ".":
                    cost = 1;
                    status = 0;
                    break;
                case "S":
                    cost = 1;
                    status = 1;
                    break;
                case "G":
                    cost = 1;
                    status = 2;
                    break;
                case "#":
                    cost = X;
                    status = 0;
                    break;
            }
            Node result = new Node((dx, dy), )
        }

        void Process(string[] args)
        {
            var inputs1 = InputIntValues(3);
            int H, W, T;
            H = inputs1[0];
            W = inputs1[1];
            T = inputs1[2];
            var s = new List<List<string>>();
            for(int y = 0; y < H; y++) {
                s[y] = new List<string>();
                string row = Console.ReadLine();
                for(int x = 0; x < W; x++) {
                    s[y][x] = row.Split()[x];
                }
            }
        }

        static List<int> InputIntValues(int length) {
            string rowInput = Console.ReadLine();
            string[] strings = rowInput.Split(' ');
            List<int> returnvalue = new List<int>(length);
            for(int i = 0; i < length; i++) {
                returnvalue[i] = int.Parse(strings[i]);
            }
            return returnvalue;
        }

        static List<List<int>> InputIntMatrix(int X, int Y) {
            var matrix = new List<List<int>>();
            for(int i = 0; i < Y; i++) {
                string row = Console.ReadLine();
                string[] strings = row.Split(' ');
                matrix[i] = new List<int>();
                for (int j = 0; j < X; j++) {
                    matrix[i][j] = int.Parse(strings[j]);
                }
            }
            return matrix;
        }

        static List<List<string>> InputStringMatrix(int X, int Y) {
            var matrix = new List<List<string>>();
            for (int i = 0; i < Y; i++) {
                string row = Console.ReadLine();
                string[] strings = row.Split(' ');
                matrix[i] = new List<string>();
                for (int j = 0; j < X; j++) {
                    matrix[i][j] = strings[j];
                }
            }
            return matrix;
        }
    }*/
}

namespace ProCon {
    class Program {
        static void Main(string[] args) {
            int A, B;
            var tmp = InputIntValues(2);
            A = tmp[0];
            B = tmp[1];
            Console.WriteLine((A - 1) * (B - 1));
        }

        static List<int> InputIntValues(int length) {
            string rowInput = Console.ReadLine();
            string[] strings = rowInput.Split(' ');
            List<int> returnvalue = new List<int>(length);
            for (int i = 0; i < length; i++) {
                returnvalue[i] = int.Parse(strings[i]);
            }
            return returnvalue;
        }

        static List<List<int>> InputIntMatrix(int X, int Y) {
            var matrix = new List<List<int>>();
            for (int i = 0; i < Y; i++) {
                string row = Console.ReadLine();
                string[] strings = row.Split(' ');
                matrix[i] = new List<int>();
                for (int j = 0; j < X; j++) {
                    matrix[i][j] = int.Parse(strings[j]);
                }
            }
            return matrix;
        }

        static List<List<string>> InputStringMatrix(int X, int Y) {
            var matrix = new List<List<string>>();
            for (int i = 0; i < Y; i++) {
                string row = Console.ReadLine();
                string[] strings = row.Split(' ');
                matrix[i] = new List<string>();
                for (int j = 0; j < X; j++) {
                    matrix[i][j] = strings[j];
                }
            }
            return matrix;
        }
    }
}