#include<stdio.h>
#include<stdlib.h>

int main(int argc,char** argv){

  FILE * fp;
  int n;
  int i;
  int count;

  if((fp=fopen("fractii.in","r"))==NULL){
     perror("cmmdc.in :");
     return 1;
  }
  
  fscanf(fp,"%d",&n);
  fclose(fp);
  
  count=n*(n-1);
  
  for(i=2;i<n;i++)
     count-=count/i;
  
  if((fp=fopen("fractii.out","w"))==NULL){
     perror("fractii.out :");
     return 1;
  }
    
  fprintf(fp,"%d",count);

  fclose(fp);
  return 0;

}