Problem:
Score : 100 points

Problem Statement

You are given two integers A and B.
Find the largest value among A+B, A-B and A \times B.

Constraints

-1000 \leq A,B \leq 1000

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B

Output

Print the largest value among A+B, A-B and A \times B.

Sample Input 1

3 1

Sample Output 1

4

3+1=4, 3-1=2 and 3 \times 1=3. The largest among them is 4.

Sample Input 2

4 -2

Sample Output 2

6

The largest is 4 - (-2) = 6.

Sample Input 3

0 0

Sample Output 3

0

Solution in C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

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

public class Hello
{
    public static void Main()
    {
        // Your code here!
        int N = int.Parse(Console.ReadLine());
        string S = Console.ReadLine();
        
        
        int max = 0;
        string alphabet = "abcdefghijklmnopqrstuvwxyz";
        
       for(int i = 1;i <= S.Length; i++)  //文字列を2つの配列に分割
       {
          
           int sum = 0;
           string X = S.Substring(0, i);
           string Y = S.Substring(i);
           foreach(char l in alphabet) //辞書は使わない
           {
               bool foundX = false;　　//あるかないかはtrue,falseを使う
               bool foundY = false;
               foreach(char x in X)
               {
                   if(x == l)
                   {
                       foundX = true;
                   }
               }
               foreach(char y in Y)
               {
                   if(y == l)
                   {
                       foundY = true;
                   }
               }
               if(foundX == true && foundY == true)
               {
                   sum++;
               }
           }
           if(sum > max)
           {
               max = sum;
           }
       }
       Console.WriteLine(max);
       
    }
}