#include <cstdio>

#include <algorithm>

#include <cmath>

#include <vector>

#define C 2730

#define S 3

using namespace std;

typedef long long ll;

ll n,m,cnt,cnf,ans;

vector<ll> v;

ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}

ll mul(ll a,ll b,ll n){return(a*b-(ll)(a/(long double)n*b+1e-3)*n+n)%n;}

ll pow(ll a, ll b, ll n){

    ll d=1; a%=n;

    while(b){

        if(b&1)d=mul(d,a,n);

        a=mul(a,a,n);

        b>>=1;

    }return d;

}

bool check(ll a,ll n){

    ll m=n-1,x,y;int i,j=0;

    while(!(m&1))m>>=1,j++;

    x=pow(a,m,n);

    for(i=1;i<=j;x=y,i++){

        y=pow(x,2,n);

        if((y==1)&&(x!=1)&&(x!=n-1))return 1;

    }return y!=1;

}

bool miller_rabin(int times,ll n){

    ll a;

    if(n==1)return 0;

    if(n==2)return 1;

    if(!(n&1))return 0;

    while(times--)if(check(rand()%(n-1)+1,n))return 0;

    return 1;

}

ll pollard_rho(ll n,int c){

    ll i=1,k=2,x=rand()%n,y=x,d;

    while(1){

        i++,x=(mul(x,x,n)+c)%n,d=gcd(y-x,n);

        if(d>1&&d<n)return d;

        if(y==x)return n;

        if(i==k)y=x,k<<=1;

    }

}

void findfac(ll n,int c){

    if(n==1)return;

    if(miller_rabin(S,n)){

        v.push_back(n);

        return;

    }ll m=n;

    while(m==n)m=pollard_rho(n,c--);

    findfac(m,c),findfac(n/m,c);

}

int main(){

    while(~scanf("%lld",&n)){

        findfac(n,C);

        sort(v.begin(),v.end());

        v.erase(unique(v.begin(),v.end()),v.end());

        ll phi=n;

        for(int i=0;i<v.size();i++){

            ll y=v[i];

            phi=(phi/y)*(y-1);

        }printf("%lld\n",phi);

    }return 0;

}