Cod sursa(job #2325654)
Utilizator | Data | 22 ianuarie 2019 20:20:24 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.53 kb |
#include <iostream>
#include <fstream>
#define NMAX 1000005
std::ifstream in("fractii.in");
std::ofstream out("fractii.out");
using namespace std;
int n,sum[NMAX];
long long sumafin;
void era()
{
for(int i=1;i<=n;i++)
{
sum[i]=i-1;
sumafin+=sum[i];
}
for(int i=2;i<=n;i++)
{
for(int j=i+i;j<=n;j+=i)
{
sum[j]-=sum[i];
sumafin-=sum[i];
}
}
}
int main()
{
in>>n;
era();
out<<sumafin*2+1;
return 0;
}