Cod sursa(job #199950)
Utilizator | Furtuna Ramona Cristina Ramona2007 | Data | 21 iulie 2008 14:19:43 |
---|---|---|---|
Problema | Fractii | Scor | 10 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.4 kb |
#include<stdio.h>
long long int i, j, N, phi[1000], k, suma;
int main()
{
freopen("fractii.in", "r", stdin);
freopen("fractii.out", "w", stdout);
scanf("%lld", &N);
for ( i=1;i<=N;i++)
phi[i]=i;
for ( i=2;i<=N;i++)
if (phi[i]==i)
for (j=i;j<=N;j+=i)
phi[j] /=i, phi[j] *= (i-1);
for(k=2;k<=N;k++)
suma=suma+phi[k];
printf("%lld", 2*suma+1);
return 0;
}