UVA - 12493 - Stars

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuffer sb = new StringBuffer("");
        String m="";
        while((m=br.readLine())!=null) {
            sb.append(compStars(Integer.parseInt(m))).append("\n");
        }
        System.out.print(sb);
    }
   
    static int compStars(int in){ 
        int ans=1; 
        int x=in;
        for(int i=2;i<=Math.sqrt(x)+1;i++){ 
            if(x%i==0){       
               x/=i; 
               ans*=(i-1); 
                while(x%i==0){ 
                    x/=i; 
                    ans*=i; 
                } 
            } 
        }
        if(x>1){ 
            ans*=(x-1);
        }
        return ans/2; 
    } 
}