POJ 2407-Relatives (evaluate the Euler's function value of an integer)

POJ 2407-Relatives (evaluate the Euler's function value of an integer)

 

Relatives Time Limit:1000 MS Memory Limit:65536KB 64bit IO Format:% I64d & % I64u Submit Status Practice POJ 2407 Appoint description: System Crawler)

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 z.

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 shocould be single line of output answering the question posed above.

Sample Input

7120

Sample Output

64

 

Question: give n a number and find the number of elements not greater than n and interacting with n.

 

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          using namespace std;typedef long long LL;const int inf=0x3f3f3f3f;const double pi= acos(-1.0);int Euler(int n){ int m=floor(sqrt(n+0.5)); int ans=n; for(int i=2;i<=m;i++){ if(n%i==0){ ans=ans/i*(i-1); while(n%i==0){ n/=i; } } } if(n>1) ans=ans/n*(n-1); return ans;}int main(){ int n; while(~scanf("%d",&n)){ if(!n) break; printf("%d\n",Euler(n)); } return 0;}