Cod sursa(job #1204253)
Utilizator | Data | 2 iulie 2014 15:15:45 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.37 kb |
#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long a[1000001],s,n;
int main()
{
f>>n;
for(int i=1;i<=n;i++)
a[i]=i-1;
for(int i=2;i<=n;i++)
for(int j=2*i;j<=n;j+=i)
a[j]-=a[i];
for(int i=2;i<=n;i++)
s+=a[i];
g<<2*s+1<<endl;
return 0;
}