Why it shows runtime error

/* package codechef; // don’t place package name! */

import java.util.;
import java.lang.
;
import java.io.*;

/* Name of the class has to be “Main” only if the class is public. */
class Codechef
{
public static void main (String[] args) throws java.lang.Exception
{
// your code goes here
Scanner sc=new Scanner(System.in);
int a=sc.nextInt();
if(a<=50) {
System.out.println(“100”);
}
else if(a>100){
System.out.println(“0”);
}
else {
System.out.println(“50”);
}
}
}