Cod sursa(job #2182693)
Utilizator | Andrei Mihailescu Andrei2000 | Data | 22 martie 2018 16:23:16 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.55 kb |
#include <bits/stdc++.h>
using namespace std;
ifstream fin ("fractii.in");
ofstream fout ("fractii.out");
long long v[1000003];
int main()
{
int n;
long long sum=0;
fin>>n;
for(int i=1;i<=n;i+=4){
v[i]=i;
v[i+1]=i+1;
v[i+2]=i+2;
v[i+3]=i+3;
}
for(int i=n-4;i<=n;++i)v[i]=i;
for(int i=2;i<=n;++i){
if(v[i]==i)
for(int j=2*i;j<=n;j+=i)
v[j]=v[j]*(i-1)/i;
sum+=(v[i]==i?i-1:v[i]);
}
fout<<2*sum+1<<'\n';
return 0;
}