Cod sursa(job #1470576)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 11 august 2015 17:39:26
Problema Fractii Scor 100
Compilator c Status done
Runda Arhiva de probleme Marime 0.31 kb
Raporteaza aceasta sursa 
#include<stdio.h>
int n,i,k,x[1000001];
long long r=1;
int main() {
	freopen("fractii.in","r",stdin),freopen("fractii.out","w",stdout),scanf("%d",&n);
	for(i=1;i<=n;i++)
       	x[i]=i;
	for(i=1;i<=n;i++)
	for(k=2*i;k<=n;k+=i)
		x[k]-=x[i];
	for(i=2;i<=n;i++)
       	r=r+2*x[i];
	printf("%lld",r);
}