Cod sursa(job #852068)
Utilizator | Data | 10 ianuarie 2013 20:18:47 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.33 kb |
#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int v[1000000],N,fra;
int main()
{ fin>>N;
for(int i=2;i<=N;i++)
v[i]=i-1;
for(int i=2;i<=N;i++)
{ for(int t=2*i;t<=N;t+=i)
v[t]-=v[i];
}
for(int i=2;i<=N;i++)
fra+=v[i];
fout<<fra*2+1;
return 0;
}