SGU 102 Coprimes

102. Coprimes

time limit per test: 0.5 sec. memory limit per test: 4096 KB

 

For given integer N (1<=N<=10⁴) find amount of positive numbers not greater than N that coprime with N.  Let us call two positive integers (say, A and B, for example) coprime if (and only if) their greatest common divisor is 1. (i.e. A and B are coprime iff gcd(A,B) = 1).

 

Input

Input file contains integer N.

 

Output

Write answer in output file.

 

Sample Input

9

Sample Output

6

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <map>
#include <queue>
#include <vector>
#include <string>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
#define maxn 105
#define ll long long
#define INF 0x7fffffff
#define eps 1e-8
int gcd(int n, int m){ return m ? gcd(m,n%m):n; }
int n, m;
int main(){
    int cas = 1;
    int t;
    while (~scanf("%d",&n)){
        //if (n == 1){ printf("1\n"); }//continue; }
        t = 0;
        for (int i = 1; i <= n; i++)
            if (gcd(i, n) == 1)t++;
        printf("%d\n", t);
        //printf("%d\n",euler(n) + 1);
    }
    return 0;
}