import java.util.Scanner;
public class Main { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); int start = scanner.nextInt(); int end = scanner.nextInt(); method(start,end); }
public static boolean isPrim(int number){
if(number <= 2 || number % 2 == 0){
return false;
}
for(int i = 3;i <= Math.sqrt(number);i+=2){
if(number % i == 0){
return false;
}
}
return true;
}
public static void method(int start, int end) {
int count=0;
//write your code here......
int temp = 0;
if(start > end){
temp = start;
start = end;
end = temp;
}
for(int i = start;i <= end;i++){
if(isPrim(i)){
count++;
}
}
System.out.println(start+"到"+end+"之间有"+count+"个大于2的素数");
}
}