Cod sursa(job #723421)
Utilizator | Data | 25 martie 2012 14:33:48 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.41 kb |
#include<stdio.h>
int n,phi[1000001];
long long ciur()
{
int i,j;
long long sol;
for(i=1;i<=n;++i)
phi[i]=i-1;
sol=1;
for(i=2;i<=n;++i)
{
sol+=phi[i];
for(j=i+i;j<=n;j+=i)
phi[j]-=phi[i];
}
return sol*2-1;
}
int main()
{
FILE*f=fopen("fractii.in","r");
fscanf(f,"%d",&n);
fclose(f);
FILE*g=fopen("fractii.out","w");
fprintf(g,"%lld\n",ciur());
fclose(g);
return 0;
}