import java.io.BufferedReader;
import java.io.InputStreamReader;
 
public class Main {
    public static void main(String[] args) throws Exception{
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        String[] params = bufferedReader.readLine().split(" ");
        int a = Integer.parseInt(params[0]);
        int b = Integer.parseInt(params[1]);
        System.out.println((b + 4) / 7 - (a + 3) / 7);
    }
}

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MSAz

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