/*
	Name: Primetive Roots  pku 1284
	Copyright: Shangli Cloud
	Author: Shangli Cloud
	Date: 01/08/14 15:49
	Description: 如果P是素数  则P有Phi(p-1)个原根 
*/
#include"iostream"
#include"cstdio"
#include"cstring"
#include"algorithm"
using namespace std;
const int ms=65540;
int phi[ms];
int main()
{
	int i,j,p;
	for(i=1;i<ms;i++)
		phi[i]=i;
	for(i=2;i<ms;i+=2)
		phi[i]/=2;
	for(i=3;i<ms;i+=2)
		if(phi[i]==i)
			for(j=i;j<ms;j+=i)
				phi[j]=phi[j]/i*(i-1);
	while(cin>>p)
		cout<<phi[p-1]<<endl;
	return 0;
}