Relatives
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 5921 | Accepted: 2606 |
Description
Given n, a positive integer, how many positive integers less than n are relatively prime to n? Two integers a and b are relatively prime if there are no integers x > 1, y > 0, z > 0 such that a = xy and b = xz.
Input
There are several test cases. For each test case, standard input contains a line with n <= 1,000,000,000. A line containing 0 follows the last case.
Output
For each test case there should be single line of output answering the question posed above.
Sample Input
7 12 0
Sample Output
6 4
#include<stdio.h>
int main()
{
int n,k;
while(scanf("%d",&n)&&n)
{
int b=n;k=2;
int res=n;
while(k<=b)
{
if(b%k==0)
{
res-=res/k;
b/=k;
}
while(b%k==0) b/=k;
if(b==1) break;
k++;
}
if(b==n) {printf("%d/n",n-1);continue;}
if(b>1&&b<n) res-=res/k;
printf("%d/n",res);
}
return 0;
}