Cod sursa(job #2494767)
Utilizator | Mircea Maierean mirceamaierean41 | Data | 18 noiembrie 2019 13:12:09 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | r_1 | Marime | 0.46 kb |
#include <fstream>
#define nmax 1000003
using namespace std;
int n,i,j;
long long T=0;
int fi[nmax];
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int main()
{
cin>>n;
for (i=1; i<=n; i++)
fi[i] = i-1;
fi[1]=1;
for (i=2; i<=n; i++)
for (j=i+i; j<=n; j+=i)
fi[j] -= fi[i];
for(i=1; i<=n; ++i)
T+=fi[i];
cout<<2*T-1;
cin.close();
cout.close();
return 0;
}