importjava.io.BufferedReader;importjava.io.InputStreamReader;publicclassN41_P11689_오일러_피_함수 {publicstaticvoidmain(String[] args) throwsException {BufferedReader br =newBufferedReader(new InputStreamReader(System.in));long n =Long.parseLong(br.readLine());long result = n;for (long p =2; p <=Math.sqrt(n); p++) {if (n % p ==0) { result = result - result / p;while (n % p ==0) { n /= p; } } }if (n >1) { result = result - result / n; }System.out.println(result); }}