#include <iostream>
#include <math.h>
#include <fstream>
#include <vector>
using namespace std;
#define N_MAXPRIMES 10000
#define N_MAXFACTORS 128

bool is_prime(long long n, vector<signed int>* primes);
int factor(long long n, int* factors);
float makephi(long long n, int* uniques, int nuniques);
int array_unique(int* elements, int count, int* uniques);
void check_validity(long long n);

int main(int argc, char *argv[]) {
	long long max = strtoll(argv[1], NULL, 10);
	//vector<signed int> primes;
	//primes.resize(N_MAXPRIMES);
	//ifstream Primes("primes_up_to_10m.txt");
	(void) check_validity(max);
	int factors[N_MAXFACTORS];
	int i = 0;
	int uniques[N_MAXFACTORS];
	int nuniques, factnum = -1;
	long maxphi;
	long long maxintphi;
	long long n = max;
	//for(n=1;n<=max;n++) {
		nuniques = -1;
		factnum = -1;
		factnum = factor(n, factors);
		/*if(factnum != 0) {
			cout << n <<": ";
			for(i=0;i<=factnum;i++) {
				cout << factors[i] << " ";
			}cout << endl;
		} else {
			cout << n << ": is prime." << endl;
		}*/
	
		if(factnum != 0) {
			nuniques = array_unique(factors, factnum, uniques);
		}
		long long phi = (signed int) makephi(n, uniques, nuniques);
		
		cout << "phi("<<n<<") = "<<phi<<endl;

		
	//}
		return 1;
}
bool is_prime(long long n, vector<signed int>* primes = 0) {
	long sqrtn = (long) sqrt(n)+1;
	int i;
	if(/*n > N_MAXPRIMES*/1) {
		for(i=2;i<=sqrtn;i++) {
			if(n % i == 0) {
				return false;
			}
		}
		return true;
	} /*else {

		for(i=2;primes->at(i) <= sqrtn;i++) {
			if(n % primes->at(i) == 0) {
				return false;
			}
		}
		return true;
	}*/
}

int factor(long long n, int* factors) {
	int i = 2;
	long long sqrtn = (long long) sqrt(n)+1;
	int factnum = 0;

	while(i<=sqrtn && factnum <= N_MAXFACTORS) {
		if((n % i) == 0) {
			factors[factnum] = i;
			/*vector<signed int>* c;
			if(1) {c=&primes;}else{c=0;}*/
			if(!(is_prime((n / i)))) {
				
				n = n/i;
				i=2;
				sqrtn = (long long) sqrt(n)+1;
			} else {
				if((n/i) != 1) {factors[++factnum] = n/i;} 
				// Duh, we already know 1 is a factor

				break;
			}
				
			factnum++;
		}else{i++;}
	
	}
	return factnum;
}

float makephi(long long n, int* uniques, int nuniques) {
	//cout << "makephi(n: "<<n<<", factnum: "<<nuniques<<")\n";
	float result = n;
	float divisor;
	int i;
	if(nuniques == -1) {if(n!=1){return (n-1);}else{return 1;}}
	for(i=0;i<=nuniques;i++) {
		divisor =  (float) (1-((float) 1/((float) uniques[i])));
		//cout << result << "*" << divisor << endl;
		result = (float) ((float)result * (float)divisor);
	//	cout << "Result so far: " << result << endl;
	}	
	return (float) result;

}

int array_unique(int* elements, int count, int* uniques) {
	int i,j = 0;
	int uniquecount = -1;
	bool error = false;
	for(i=0;i<=count;i++) {
		error = false;
		for(j=0;j<=uniquecount;j++) {
			if(elements[i] == uniques[j]) {
				error = true;
			}
		}
		if(!error) {
			uniquecount +=1;
			uniques[uniquecount] = elements[i];
		}
	}
	return uniquecount;

}
void check_validity(long long n) {
	if(n<0) {
		cout << "Error: Negative number.\n";
		exit(1);
	}else if(n==1) {
		cout << n << ": is a unit.\n";
		exit(1);
	}else if(n==0) {
		cout << n << ": is a zero-divisor.\n";
		exit(1);
	}
}