Cod sursa(job #877862)
Utilizator | Data | 13 februarie 2013 12:56:24 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.44 kb |
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int e[1000001];
int main()
{
int i,n,j;
in>>n;
for(i=2;i<=n;i++){
e[i]=i;
}
for(i=2;i<=n;i++){
if(e[i]==i){
for(j=i;j<=n;j+=i){
e[j]=e[j]/i*(i-1);
}
}
}
j=0;
for(i=2;i<=n;i++){
j+=e[i];
}
out<<2*j+1;
return 0;
}