Cod sursa(job #395261)
Utilizator | mihai995 mihai995 | Data | 12 februarie 2010 17:35:33 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.29 kb |
#include <fstream>
using namespace std;
int v[1000001];
int main()
{
int i,j,n;
long long nr=0;
ifstream f("fractii.in");
ofstream o("fractii.out");
f>>n;
for (i=2;i<=n;i++)
{
v[i]=v[i]+i-1;
for (j=2*i;j<=n;j+=i)
v[j]-=v[i];
nr+=v[i];
}
o<<2*nr+1;
return 0;
}