import java.io.*;

class SommaDue {
  public static void main(String args[])
  throws IOException {
    FileReader f;
    f=new FileReader("numeri.txt");

    BufferedReader b;
    b=new BufferedReader(f);

    String s;
    int x;

    while(true) {
      s=b.readLine();
      if(s==null)
        break;

      x=Integer.parseInt(s);
      System.out.println(x+2);
    }
  }
}