#include<stdio.h>

long long i,j,nr,n,k,sol[1000003];

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%lld",&n);
    nr=n;
    for(i=2;i<=n;i++)
         if (!sol[i])               
         {
             k=i;if (n%i==0)
                    nr=(i-1)*nr/i;
             for (j=i+k;j<=n;j+=k)
                 sol[j]=1;
         }
    printf("%lld",&nr);
    return 0;
}