Cod sursa(job #3220690)
Utilizator | Data | 4 aprilie 2024 17:27:01 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.42 kb |
#include <fstream>
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int n, euler[1000005];
int ciur(int n){
int ans = 0;
for(int i = 2; i<=n; i++)euler[i] = i-1;
for(int i = 2; i<=n; i++){
ans+=euler[i];
for(int j = i * 2; j<=n; j+=i){
euler[j]-=euler[i];
}
}
return ans * 2 + 1;
}
int main() {
cin >> n;
cout << ciur(n);
return 0;
}