#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
inline int read(){
    int x=0,f=1;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch=‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}
int n,phi,tot,ans,num[500010],sum=1;
int gcd(int a,int b){
    if(!b) return a;
    return gcd(b,a%b);
}
int main(){
    phi=n=read(); int tmp=n;
    for(int i=2;i*1ll*i<=tmp;++i){
        if(tmp%i==0){
            ++tot; phi=phi/i*(i-1);
            while(tmp%i==0){ ++num[tot]; tmp/=i;}
        }
        if(tmp==1) break;
    }
    if(tmp>1){phi=phi/tmp*(tmp-1); num[++tot]=1;}
    for(int i=1;i<=tot;++i)
    sum=sum*(num[i]+1);
    printf("%d\n",n-phi-sum+1);
    return 0;
}