Cod sursa(job #1436780)
Utilizator | Data | 16 mai 2015 13:25:00 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.38 kb |
#include<iostream>
#include<fstream>
using namespace std;
int main () {
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long int n, i, j, nr=0;
fin>>n;
long int v[n];
for (i=1; i<=n; i++)
v[i]=i;
for (i=2; i<=n; i++)
if(v[i]==i)
for(j=i; j<=n; j+=i)
v[j]=v[j]/i*(i-1);
for (i=1; i<=n; i++)
nr+=2*v[i];
fout<<nr-1;
return 0;
}