49 lines
786 B
C++
49 lines
786 B
C++
#include<cstdio>
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#include<cstring>
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#include<algorithm>
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using namespace std;
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typedef long long LL;
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const int maxn=65536;
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int p[maxn],v[maxn],ph[maxn],cnt;
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LL n,res;
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inline int phi(int x)
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{
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LL res=x;
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for(LL i=2;i*i<=x;i++) if(x%i==0)
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{
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res=res/i*(i-1);
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while(x%i==0) x/=i;
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}
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if(x>1) res=res/x*(x-1);
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return res;
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}
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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/*
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ph[1]=1;
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for(int i=2;i<maxn;i++)
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{
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if(!v[i]) { v[i]=i; ph[i]=i-1; p[cnt++]=i; }
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for(int j=0;j<cnt&&(long long)p[j]*i<maxn&&p[j]<=v[i];j++)
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{
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v[p[j]*i]=p[j];
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ph[p[j]*i]=ph[i]*(p[j]<v[i]?p[j]-1:p[j]);
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}
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}
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*/
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while(scanf("%d",&n)==1)
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{
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res=0;
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for(LL i=1;i*i<=n;i++) if(n%i==0)
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{
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res+=i*phi(n/i);
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if(i*i<n) res+=n/i*phi(i);
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}
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printf("%lld\n",res);
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}
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return 0;
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}
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