import java.util.*;
public class Main{
    public static void main(String[] args){
        
        Scanner s = new Scanner(System.in);
        String n = s.next();
        
        for(int itr = 0; ite < n.length(); itr++){
            char c = n.charAt(itr);
            
            if(!Character.isDigit(c)){
                System.out.println("false");
                return;
            }
        }
        System.out.println("true");
        
    }
}