找不能约分的分数，既找分子分母互质的分数


#include <iostream>#include <cstdio>#include <algorithm>using namespace std;typedef long long ll;#define max 1000010ll phi[max];int n;void getphi(){	for(int i=0;i<max;i++)phi[i]=0;	phi[1]=1;	for(int i=2;i<max;i++){		if(!phi[i]){			for(int j=i;j<max;j+=i){				if(!phi[j])phi[j]=j;				phi[j]=phi[j]/i*(i-1);			}		}	}}int main(){	getphi();	//freopen("test.txt","r",stdin);	while(cin>>n){			if(n==0)break;		ll sum=0;		for(int i=2;i<=n;i++){			sum+=phi[i];		}		cout<<sum<<endl;	}}