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uva10179.cpp
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uva10179.cpp
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using namespace std;
#include<iostream>
#include<cstring>
#include<cstdio>
#include<math.h>
#include<vector>
#define N 100000+10
#define ll long long int
bool prime[N];
vector<int>primes;
void sieve()
{
long i,j;
prime[0]=prime[1]=true;
primes.push_back(2);
for(i=4;i<N;i+=2)
prime[i]=true;
for(i=3;i<=1000;i++)
{
if(prime[i]==false)
{
primes.push_back(i);
for(j=i*i;j<N;j+=2*i)
prime[j]=true;
}
}
while(i<N)
{
if(prime[i]==false)
primes.push_back(i);
i+=2;
}
}
ll phi(ll n)
{
ll ans=n,j,sz=primes.size(),sq=sqrt(n);
for(j=0;j<sz&&primes[j]<=sq;j++)
{
if(n%primes[j]==0)
{
ans=ans-ans/primes[j];
while(n%primes[j]==0)
n/=primes[j];
}
if(n==1) break;
}
if(n>1) ans=ans-ans/n;
return ans;
}
int main()
{
sieve();
ll n;
while(scanf("%lld",&n)==1&&n)
{
printf("%lld\n",phi(n));
}
return 0;
}