Problem:
Score : 100 points

Problem Statement

In K-city, there are n streets running east-west, and m streets running north-south. Each street running east-west and each street running north-south cross each other. We will call the smallest area that is surrounded by four streets a block. How many blocks there are in K-city?

Constraints

2 ≤ n, m ≤ 100

Input

Input is given from Standard Input in the following format:

n m

Output

Print the number of blocks in K-city.

Sample Input 1

3 4

Sample Output 1

6

There are six blocks, as shown below:

Sample Input 2

2 2

Sample Output 2

1

There are one block, as shown below:

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

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

namespace easy_Atcoder
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] nm = Array.ConvertAll(Console.ReadLine().Split(),int.Parse);
            Console.WriteLine((nm[0]-1)*(nm[1]-1));
        }
            // float[] ABN = Array.ConvertAll(Console.ReadLine().Split(),float.Parse);
            // long[] NK = Array.ConvertAll(Console.ReadLine().Split(),long.Parse);
            // long N = NK[0];
            // long K = NK[1];
            // long K = long.Parse(Console.ReadLine());
            // int[] abc = Array.ConvertAll(Console.ReadLine().Split(),int.Parse);
            // string S = Console.ReadLine();
            // int x = int.Parse(Console.ReadLine());
            // int b = int.Parse(Console.ReadLine());
            // int N = int.Parse(Console.ReadLine());
            // float N = float.Parse(Console.ReadLine());
            // string c = Console.ReadLine();
            // string B = Console.ReadLine();
            // string[] s = Console.ReadLine().Split();
            // var s = (new string[] { Console.ReadLine(), Console.ReadLine(), Console.ReadLine() }).Select(float.Parse);
            // float[] a = Array.ConvertAll(Console.ReadLine().Split(),float.Parse);
            // var X = Console.ReadLine();
            // int[,] abcd = new int[NMQ[2],4];
            // int[] A = new int[NMQ[0]];
            // int[] A_num = new int[NMQ[0]];
            // long[] s=Array.ConvertAll(Console.ReadLine().Split(),long.Parse);
            // var hs=new Dictionary<long,long>();
            // for(int i=0;i<s[0];i++){
            //     long[] q=Array.ConvertAll(Console.ReadLine().Split(),long.Parse);
            //     if(hs.ContainsKey(q[0])){hs[q[0]]+=q[1];}
            //     else{hs.Add(q[0],q[1]);}
            // }
        
        // //最小公倍数
        // static long Lcm(long a, long b)
        // {
        //     return a/Gcd(a,b)*b;
        // }

        // //最大公約数
        // static long Gcd(long m, long n)
        // {
        //     if(n==0)return m;
        //     return Gcd(n,m%n);
        // }
    }
}