Cod sursa(job #187568)
Utilizator | Popescu Marius jupanubv92 | Data | 4 mai 2008 18:40:57 |
---|---|---|---|
Problema | Fractii | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.38 kb |
#include<stdio.h>
int main()
{long long n,i,nr,j,phi[10000001];
freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%lld",&n);
nr=0;
for (i = 1; i <= n; ++i)
phi[i] = i-1;
for (i = 2; i <= n; ++i)
for ( j = 2*i; j <= n; j += i)
phi[j] -= phi[i];
for(i=1;i<=n;i++)
nr=nr+phi[i];
printf("%lld",nr*2+1);
return 0;
}