Cod sursa(job #355340)
Utilizator | Panaete Adrian proflaurian | Data | 10 octombrie 2009 19:19:28 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.37 kb |
#include<stdio.h>
int n,i,j,p,a[1000001];
long long S;
void read(),solve();
int main()
{
read();
solve();
return 0;
}
void read()
{
freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%d",&n);
}
void solve()
{
for(i=2;i<=n;i++)a[i]=i-1;
for(i=2;i<=n;i++)
{
S+=a[i];
for(j=i+i;j<=n;j+=i)a[j]-=a[i];
}
S*=2;S++;
printf("%lld\n",S);
}