Problem:
Score : 100 points

Problem Statement

Takahashi has K 500-yen coins. (Yen is the currency of Japan.)
If these coins add up to X yen or more, print Yes; otherwise, print No.

Constraints

1 \leq K \leq 100

1 \leq X \leq 10^5

Input

Input is given from Standard Input in the following format:

K X

Output

If the coins add up to X yen or more, print Yes; otherwise, print No.

Sample Input 1

2 900

Sample Output 1

Yes

Two 500-yen coins add up to 1000 yen, which is not less than X = 900 yen.

Sample Input 2

1 501

Sample Output 2

No

One 500-yen coin is worth 500 yen, which is less than X = 501 yen.

Sample Input 3

4 2000

Sample Output 3

Yes

Four 500-yen coins add up to 2000 yen, which is not less than X = 2000 yen.

Solution in C# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;

namespace vscode
{
    class Program
    {
        static void Main(string[] args)
        {
            int length = int.Parse(Console.ReadLine());
            string testee = Console.ReadLine();

            int cntAbc = matchWords(testee.ToCharArray(), "ABC".ToCharArray(), length);

            Console.WriteLine(cntAbc);
        }

        static int matchWords(char[] testee, char[] matcher, int length) {
            if (length < 3 || length > 50) return 0;

            int found = 0;
            int pos=0;
            int vurpos=0;
            
            while(pos <= length-1) {
                if (testee[pos] == matcher[vurpos]) {
                    vurpos++;
                    if(vurpos == 3){
                        found++;
                        vurpos=0;
                    }

                } else {
                    vurpos=0;
                }

                pos++;
            }
            return found;
        }
    }
}