Cod sursa(job #524469)
Utilizator | Data | 21 ianuarie 2011 18:07:00 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.29 kb |
#include <fstream.h>
#include <iostream.h>
ifstream f("fractii.in");
ofstream g("fractii.out");
long a[1000000];
int main(){
long nr,n,i,j;
f>>n;
for(i=2;i<=n;++i)
a[i]=i-1;
nr=0;
for(i=2;i<=n;++i){
nr+=a[i];
for(j=i*2;j<=n;j+=i)
a[j]-=a[i];
}
nr=2*nr+1;
g<<nr;
return 0;
}