Language: Java

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int MAX=20000;
        int MIN=0;
        
        while(true){
            String[] data=reader.readLine().split(" ");
            final int a=Integer.parseInt(data[0]);
            final int b=Integer.parseInt(data[2]);
            
            if(data[1].equals("?")) break;
        
            if((MIN<=a && a<=MAX) && (MIN<=b && b<=MAX)){
                if(data[1].equals("+")) System.out.print(a+b\n);
                else if(data[1].equals("-")) System.out.print(a-b\n);
                else if(data[1].equals("*")) System.out.print(a*b\n);
                else if(data[1].equals("/")) System.out.print(a/b\n);
            }
        }
    }
}

Compiler output:
Main.java:18: error: illegal character: '\'
                if(data[1].equals("+")) System.out.print(a+b\n);
                                                            ^
Main.java:18: error: not a statement
                if(data[1].equals("+")) System.out.print(a+b\n);
                                                             ^
Main.java:18: error: ';' expected
                if(data[1].equals("+")) System.out.print(a+b\n);
                                                              ^
Main.java:19: error: illegal character: '\'
                else if(data[1].equals("-")) System.out.print(a-b\n);
                                                                 ^
Main.java:19: error: 'else' without 'if'
                else if(data[1].equals("-")) System.out.print(a-b\n);
                ^
Main.java:19: error: not a statement
                else if(data[1].equals("-")) System.out.print(a-b\n);
                                                                  ^
Main.java:19: error: ';' expected
                else if(data[1].equals("-")) System.out.print(a-b\n);
                                                                   ^
Main.java:20: error: illegal character: '\'
                else if(data[1].equals("*")) System.out.print(a*b\n);
                                                                 ^
Main.java:20: error: 'else' without 'if'
                else if(data[1].equals("*")) System.out.print(a*b\n);
                ^
Main.java:20: error: not a statement
                else if(data[1].equals("*")) System.out.print(a*b\n);
                                                                  ^
Main.java:20: error: ';' expected
                else if(data[1].equals("*")) System.out.print(a*b\n);
                                                                   ^
Main.java:21: error: illegal character: '\'
                else if(data[1].equals("/")) System.out.print(a/b\n);
                                                                 ^
Main.java:21: error: 'else' without 'if'
                else if(data[1].equals("/")) System.out.print(a/b\n);
                ^
Main.java:21: error: not a statement
                else if(data[1].equals("/")) System.out.print(a/b\n);
                                                                  ^
Main.java:21: error: ';' expected
                else if(data[1].equals("/")) System.out.print(a/b\n);
                                                                   ^
15 errors